Reference to Preissia guadrata." For both this and Llie f(;lIow- 

 ing paper microscopic slides demonstrating the various stages 

 were placed on view. 



Miss Graham reviewed the work on fertilization in the liver- 

 worts, as follows: 



In 1891, Kruch observed that the antherozoids of Riella 

 Clausonia enlarge at once upon entering the cytoplasm of the 

 egg and that the body of the male pronucleus divides into eight 

 chromosomes. The two pronuclei become almost eciual in size 

 when in contact. 



Rickett (1923) observed that both the male and female 

 pronuclei in Sphaerocarpus form chromosomes and that the 

 nuclear membrane of each breaks down. 



Humphrey (1906) observed the antherozoid when still a 

 curved rod. lying in contact with the eg^ nucleus of Fossombronia 

 longiseta. 



In Ricciacarpus nutans, Garber (1904) observed that the male 

 pronucleus was half the size of the female pronucleus and that 

 they were in contact. 



In Riccia Frostii, Miss Black (19 13) observed the male pro- 

 nucleus in the egg cytoplasm near the female pronucleus. 



Woodburn (1914) observed the two pronuclei in the cytoplasm 

 of Reboulia hemispherica, Sharpe (1921) made a similar observa- 

 tion for Anthoceros and Mayer (191 1) for Corsinia Marchan- 

 toides. 



In Preissia quadrata, Miss Graham observed that the anthero- 

 zoid enlarges at once upon entering the cytoplasm of the egg 

 and moves near to but not in contact with the female pronucleus. 

 At this time a centrosphere may be observed in the egg cytoplasm 

 near the antherozoid. While the antherozoid is in this position, 

 diflferentiation takes place, resulting in a t^^pical nucleus in 

 prophase. The contents of the female pronucleus before fer- 

 tilization is massed around the nucleolus; after fertilization, 

 however, the nucleus enlarges and its chromatin appears in 

 masses, thin threads running between them. At opposite poles 

 of the female pronucleus centrospheresmay be seen. 



The second paper was by Dr. Mabel L. Merriman, also of 

 Hunter College, the subject being "Some Changes in the Cell 

 Contents of Spirogy^ra during Conjugation." 



Dr. Merriman said that after the union of the gametangia 



