Mat 26, 1911] 



JSGIENOE 



819 



denying soma influence, the results in tliis 

 case might as well lead to the conclusion that 

 the ofFspring were from ovarian tissue of the 

 mother, as from the engrafted ovarian tissue. 

 Also in the remaining animal, from the de- 

 scription given of the post-mortem findings it 

 is impossible to conclude that the mother's 

 ovarian tissue was completely removed on 

 both sides. This objection the authors en- 

 deavor to surmount by stating that the mass 

 of ovarian tissue found at the site from which 

 the right ovary was removed, was apparently 

 strongly encapsulated, so that no ovum could 

 be discharged even if it came to maturity. 

 Such a conclusion is of course incompatible 

 with the evidence, for few experienced pathol- 

 ogists, from the evidence presented, would 

 care to make such a definite statement as to 

 the retention of liberated ova. 



Similarly, their statements regarding the 

 regeneration of ovarian tissue are too abso- 

 lute. For example, in certain cases where 

 both ovaries were removed and ovaries from 

 another animal engrafted in the neighbor- 

 hood, as to the horn of the uterus, the absence 

 of ovarian tissue at the site of implantation, 

 and the presence of ovarian tissue at the site 

 of removal of the animal's own ovaries is not 

 proof that the former degenerated, and the 

 latter regenerated. For it is possible that the 

 implanted ovaries might have come in contact 

 with the raw surface left after removal of the 

 original ovaries, and become attached thereto. 

 And since the engrafted ovaries were secured 

 in place by means of exceedingly fine strands 

 of unraveled silk, it is by no means certain 

 that they could not have broken away from 

 their moorings, owing to a cutting out of the 

 tissues or a slipping of the knots, or even a 

 breaking of the thread; though the latter 

 accident would probably be less liable to occur. 



These are merely some points that it is 

 unsafe to leave out of account in concluding 

 that such experiments are critical in the ab- 

 solute sense, and I wish to say that I do not 

 urge them as invalidating their results. In 

 fact I consider that they have added at least 

 one more confirmatory observation upon the 

 reproductive functioning of transplantated 



ovaries, probably two, and possibly five. For 

 the evidence does not absolutely rule out the 

 animals which they have placed in the group 

 in which they think regeneration of the 

 ovarian tissue occurred. But it should not 

 be forgotten that conclusions based upon indi- 

 rect evidence, though appearing absolute, are 

 never wholly free from at least a shadow of 

 doubt. To accept this statement, it is only 

 necessary to trace almost any biological sub- 

 ject developed from indirect experimentation 

 a little way back into the literature. Indeed, 

 teachings based upon such conclusions have 

 passed without question through generations, 

 to be later overthrown. And since the ele- 

 ment of indirectness has not been eliminated 

 in the experimental investigation of ovarian 

 transplantation, I have stated that my results 

 seem to lead to certain conclusions. And the 

 same applies to Castle and Phillips's results 

 as regards functioning of engrafted ovaries. 



As to their interpretation of the results 

 from the Mendelian standpoint, the nature of 

 some objections to their conclusions has been 

 discussed above. In addition, I would say 

 that it is unfortunate that they did not pre- 

 serve the individuals furnishing an ovary for 

 engrafting, leaving the other ovary in place 

 and then breeding this female to the same 

 male used upon the female carrying the en- 

 grafted ovary. From their paper it would 

 seem that they look chiefly to the second gen- 

 eration for evidence of soma influence, the 

 index for detecting such influence being based 

 upon the assumption that such influence 

 would show in the second generation. The 

 fallacy of this assumption has also been con- 

 sidered above. 



In conclusion, I desire to say that the con- 

 tinuation and extension of these experiments 

 is of the greatest interest and importance, 

 and I hope that Professor Castle and his pupil 

 may see their way clear to continuing them 

 on a larger scale, using purer varieties of 

 animals, including fowls of not too distantly 

 related varieties. 



0. C. Guthrie 



Physiological Laboratobt, 

 "University op Pittsburgh 



