292 CALKINS. [Vol. XI. 



3d. The residual mass of cytoplasm thus formed — the 

 blastophore — is not nucleated and cannot be compared with a 

 Sertoli cell in function, form, or mode of origin. It finally 

 disappears. The blastophore furnishes perhaps the chief 

 source of food supply for the parasites — Monocystis — which 

 live in the seminal vesicles. A possible explanation of the 

 function of the blastophore is that it represents superfluous 

 nutritive cytoplasm, the vital protoplasm having gathered 

 around the nuclei. 



4th. There is a reducing division in the number of chro- 

 mosomes and in the quantity of chromatin. In the sperma- 

 togonium thirty-two single chromosomes divide, giving thirty- 

 two to each spermatocyte of the first order. During the 

 succeeding resting stage the chromatin substance, nucleus, 

 and entire spermatosphere become enlarged. The chromatin 

 emerges as a double skein. It divides by transverse division 

 into thirty-two double chromosomes, and these unite two by 

 two to form sixteen quadruple chromosomes. Reduction in 

 number thus takes place without the aid of karyokinesis. In 

 spermatocytes of the second order the nuclei contain sixteen 

 double chromosomes. In the succeeding division these double 

 chromosomes divide, and spermatids result, each with sixteen 

 single chromosomes. 



5th. Metamorphosis of the spermatid takes place inde- 

 pendently of external conditions. The nucleus or head is 

 formed from the entire chromatin. TJie arcJioplasm of the 

 spermatid forms the middle-piece of the spermatozoon. 



6th. The archoplasm mass persists throughout every change 

 of the cell. In the preparatory stages of cell division it divides 

 to form the poles of the karyokinetic spindle, as well as the 

 spindle fibres themselves. All evidence points to the conclu- 

 sion that, during the anaphase, the spindle fibres are partly 

 withdrawn into the archoplasm. The interzonal fibres prob- 

 ably form the Ncbenkern^ which lies quiescent within the cell 

 and finally disappears. 



7th. The archoplasm mass is affected by the method of 

 treatment. After Hermann's fluid it remains large and con- 

 spicuous, both at the spindle poles and in the resting cells. 



