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THE AMERICAN NATURALIST [Vol. XLI 



In the case of the bee these conditions are better understood. 

 It appears as a rule that all unfertilized eggs produce males, and 

 all fertilized eggs produce females. The latter result must be due 

 to all the sperm being female producers, or to only female sperm 

 being capable of entering the egg, or to a quantitative relation, 

 namely, the combined nuclei producing female characters and the 

 single nucleus producing male characters. If we are justified in 

 extending to the bee the conclusion reached above for the moth 

 we can decide amongst these three interpretations. If the gynan- 

 dromorphous bee is due to one sperm nucleus fusing with tlie egg 

 nucleus and one (or more) sperm nucleus failing to fuse but devel- 

 oping alone, then the sperm are not female-producing but alone 

 are male-producing. The egg nucleus alone is also male-producing 

 as seen in the development of drones. Combined, however, these 

 two male-producing nuclei give rise to a female-producing nucleus. 

 If this conclusion proves to be correct it throws an interesting 

 light on one of the ways in which sex determination is accomplished. 



Equally important is the conclusion to which we are led in regard 

 to the relative influence of the spermatozoon versus that of the egg- 

 protoplasm — a question, as we have seen, on which the experi- 

 mental embryological evidence is still in doubt. The sperm 

 supplied with egg protoplasm gives rise in the adult to paternal 

 characters only, even in those cases like the present one in which 

 the egg carries the dominant characters! If we think of the 

 spermatozoon as introducing a nucleus only, the paternal char- 

 acters may be attributed to the nucleus; if we think of the sperma- 

 tozoon as introducing also some cytoplasm — the centrosphere 

 for example — the results might In- siip|)ii>e(] to l)e due either to 

 the introduced nucleus, or to the iinnxhicrd cytoplasm, or to both. 

 Since however the egg also sup})H('s (ytophisiii (and that of the 

 dominant kind in the present case) this would offset that of the 

 spermatozoon. It seems therefore that the nucleus is the essential 

 factor. Thus our analysis furnishes a clue as to what part of the 

 sperm carries the factors that determine the characters of the 

 adult organism. 



Columbia Univeksity, New York 

 Sept. 15, 1907 



