After 03:58 in this YouTube clip from Star Trek TOS episode Journey to Babel there's a moment where McCoy is performing surgery on Sarek using a static medical arch-like device over Sarek's chest.

At one moment smoke can be seen rising from behind the device, at least in this particular YouTube clip.

Question: Why can smoke be seen coming from McCoy's surgery on Sarek? Is this in-universe smoke, or perhaps a short circuit in a prop, or does DeForest Kelley have a cigarette back there and is sneaking puffs between takes?

from Star Trek TOS episode Journey to Babel https://www.youtube.com/watch?v=INkQsOvrmLo

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    Mentioned but not explained in the Nitpicker's Guide - "It almost looks as if someone has a cigarette back there." Commented Oct 7, 2021 at 4:42
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    worth noting that its also asked on movies.stackexchange.com/questions/78130/… - my answer (the correct one imo ;) wasn't there so I added it after answering here
    – NKCampbell
    Commented Oct 7, 2021 at 4:55
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    @OrganicMarble ya it really does look just like that. I wonder, did DeForest Kelley smoke? Actually... did anybody not smoke back then?
    – uhoh
    Commented Oct 7, 2021 at 12:29
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    @OrganicMarble - i.pinimg.com/originals/49/86/5f/…
    – NKCampbell
    Commented Oct 7, 2021 at 13:41
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    @uhoh I was alive back then, and older than many kids who start smoking, and I have never smoked. The surgeon general's report that smoking caused lung cancer came out in 1964, several years earlier, so people who were not already addiction to nicotine had a good not to try it, and many did not. Commented Oct 7, 2021 at 17:15

1 Answer 1


According to StarTrek.com it's a deliberate effect intended as "cryogenic fog" from the cryogenic-surgery (mispronounced as 'serogenic' in the episode)

Question: In “Journey to Babel,” Sarek (Mark Lenard) becomes critically ill while being transported on the Enterprise and, according to Mr. Spock, needs a “serogenic” surgical procedure on his heart to repair it. What’s a serogenic surgical procedure?

Answer: That’s a good question. Checking the script, it appears that the word “cryogenic” – which relates to very low temperatures – was mispronounced as serogenic by Nimoy. Here’s the dialogue from the script:


I’d say a cryogenic open-heart procedure is the logical approach.

As further proof that the word cryogenic was intended, the surgery that McCoy (DeForest Kelley) later performs on Sarek makes use of a “cryosurgical frame” that generates fog from condensed atmospheric water caused by the very cold temperature. (The effect was likely created by the effects team using smoke or dry ice).

hat-tip to https://www.trekbbs.com/threads/journey-to-babel-deforest-kelley-smoking.300756/ for the link

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    Wow there's a real world heart treatment called cryoablation that is used to kill tissue causing crazy nerve signals. youtu.be/z91_9Si4wQ0 Commented Oct 7, 2021 at 5:35
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    @lucasbachmann - the StarTrek.com article quoted claims that it is "cryogenic" in the script. And the medicine to ramp up blood cell production was taken by Spock, so that he could be a blood donor during the surgery, as they did not have the right type (or enough of it) in the blood bank.
    – Basya
    Commented Oct 7, 2021 at 7:32
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    I'm guessing that "cryogenic" got either misspelt or misread as "cyrogenic". That would sound like "serogenic".
    – A. B.
    Commented Oct 7, 2021 at 8:45
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    @lucasbachmann if we're being pedantic, a serogenic procedure would be one that generated serum or would describe something created by serum. Since serum does not contain blood cells, if you were to coin a word for a procedure whose aim is to ramp up blood production, you'd opt for something like haematogenic instead or, more likely, the word actually used in our world for such processes: hematopoietic. Either way, serogenic would not be related to blood cells.
    – terdon
    Commented Oct 7, 2021 at 16:09
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    It is worth noting that McCoy talks about filtering out the human elements of Spock's blood that you do see tubes with red and green fluids in them. Commented Oct 7, 2021 at 17:12

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