124 KATHARINE FOOT AND E. C. STROBELL. 



reached opposite poles of the spindle, though in these cases the 

 chromosomes at the poles are too crowded to be counted. We 

 interpret this lagging chromosome as a univalent, being equal in 

 value to all the other chromosomes of the second spindle, just as 

 in the first spindle we interpret the lagging chromosome as a 

 bivalent both cases indicating simply a retarded division of 

 one of the chromosomes. 



Our preparations do not support Wilson and Montgomery in 

 their observation that the lagging chromosome goes over undivided 

 to one pole of the second spindle, and we are therefore unable to 

 follow them in supporting McClung's theory of the dimorphism 

 of the spermatozoa. 



If these authors are correct in interpreting this lagging chromo- 

 some as only half of a univalent, what is the significance of the 

 frequent transverse constriction? What can such a constriction 

 mean but foreshadowing a division ? and this interpretation is 

 supported by the cases in which the division of this chromosome 

 is actually demonstrated. We do not interpret the presence of 

 a lagging chromosome in the first or second spindle as neces- 

 sarily an abnormal condition though it may be a step in that 

 direction, for we have seen unmistakably pathological spindles 

 where sometimes one and sometimes two chromosomes pass to 

 one pole undivided. We have photographs of some of these 

 spindles and their pathological character can be readily recog- 

 nized. We also have examples of such unequal, abnormal 

 separation of the chromosomes in the first and second spindles 

 of Allolobophora fa'tida. 



Spennatogonial Chromosomes. Paulmier ('99) who was the 

 first to study the spermatogenesis of this form interpreted the 

 number of spermatogonial chromosomes to be 22 and in his 

 Fig. 9 has reproduced one of his sections in which 22 chromo- 

 somes are clearly represented. 



Montgomery ('01) supports Paulmier in his estimate of the 

 number of spermatogonial chromosomes and in his Fig. 74 gives 

 a very clear demonstration of this number. 



Wilson in his "Studies on Chromosomes, No. I," corrects 

 this original count of the spermatogonial chromosomes with such 

 positive assurance ' that we have great hesitation in questioning 



