STUDIES OF REPRODUCTIVE ELEMENTS: 11. 3]^5 



separated from each otlier Ijy a transverse line. Stained witli Beule s 

 enrmine, tlie former colours much more (jiiickly than the latter. The 

 same state of things was ohserved l)y this author in Lepto- 

 discus med u soi des (24, p. oll), the only representative of 

 Cystofl;i gel lata, other than Noctiluca, found hy Hertwig at 

 Messiiin. The nucleus consists here also of two parts, '' einem fein- 

 k()rnigen und einem homogenen." " In dem einen Falle war die 

 homogene Ivernsnbstanz unverändert, dao-eg-en fanden sich in der 

 feink()riiigen grössere nnd kleinere Körperchen, die sicli in Carmin 

 dunkler iarl)ten und otfenbar eine bedentendere Dichtigkeit besassen. 

 In anderen Fall liess sich die Düferenzierunii- in zwei Substanzen 

 nicht nachweisen " (24, p. 31:?). The first change that occurs in 

 tlie homogeneous part of the S pi roch on a nucleus before its division 

 is the appearance of a small central corn (23, p. 161). This he 

 calls a " nucleolus," which is very probably the free area around the 

 centros(3me, such as is repreaented in my Fig. lo. Some changes occur 

 in the granular part also, and the nucleus soon assumes an elongated 

 form with homogenecjus masses placed at its poles. In this way the 

 nucleus assumes a form in which five parts are distinctly to be 

 made out : viz., two homogeneous terminal plates, two striated 

 portions, and a granular median part, considered Ijy Her(iri(j to cor- 

 respond with the nuclear plate. There is tlius a remarkable resem- 

 blance between the homogeneous part of the Spirochona nucleus 

 and the archo[)lasm (jf Noctiluca, although the aspects of the two 

 are different, the former looking transparent and the latter granular. 

 But no one will doubt of this similarity, who conq)ares my Fig. 

 14 or 52 witli Hertiriifs Fig. 17, a. What transformations the homo- 

 geneous part of the Spirochona nucleus undergoes during the 

 division is not quite clear from Herkuig^s descriptions. From what 

 we get from the Noctiluca nucleus, it seems very proljable that 



