MUSEUM OF COMPARATIVE ZOOLOGY. 9 



ment of any degree. Some of the topics treated of were : The 

 structure of protoplasm with relation to its chemical and physical 

 qualities ; The structure of the nucleus and the mechanism of 

 cell-division ; The de novo formation of centrosomes and the hy- 

 pothesis of their individuality ; The reduction division in ovogene- 

 sis and spermatogenesis, with special reference to the formation 

 of tetrads ; The meaning of fertilization and of parthenogenesis, 

 both natural and artificial. 



Researches (Zoology 20) were carried on during the year by 

 thirteen students. Of these two were under the supervision of 

 Professor Castle, three under Professor Parker, and eight under 

 Professor Mark. As in the preceding year, additional time for 

 research work was in a few cases gained by allowing the student 

 to meet the laboratory requirements in some of the formal courses 

 (11 and 15) by devoting his laboratory time in those courses to 

 the topic of his research. Of the two students working under the 

 guidance of Professor Castle, one — Mr. G. M. Allen — has pre- 

 sented the results of his studies in the form of a thesis for the 

 Ph.D. degree. The studies of the other have resulted in showing 

 that the alternative conditions of the optic chiasma in certain 

 bony fishes are not hereditary. Satisfactory progress has been 

 made by those carrying on their work under the supervision of 

 Professors Parker and Mark. Messrs. F. W. Carpenter, Grant 

 Smith, and Porter E. Sargent have presented the results of their 

 work as theses for the doctor's degree, and the theses have been 

 approved by special committees appointed to examine and report 

 upon them. 



In June, 1904, the degree of Doctor of Philosophy was conferred 

 on three candidates in Zoology : Mr. Glover Morrill Allen, whose 

 thesis was on " The Heredity of Coat Color in Mice ; " Mr. 

 Frederic Walton Carpenter, whose thesis was on " The Develop- 

 ment of the Oculomotor Nerve, the Ciliary Ganglion, and the 

 Abducent Nerve in the Chick ; " and Mr. Grant Smith, whose 

 thesis was entitled " On the Eyes of Certain Pulmonate Gastro- 

 pods, with Special Reference to the Neurofibrils in Limax 

 maximus." 



Professor Parker has conducted experiments on the lateral-line 

 organs of fishes for the United States Fisheries Bureau, and, in 

 conjunction with Miss Adele M. Fielde, on reactions of ants to 

 material vibrations. He has also delivered a number of public 

 lectures at the Brooklyn Institute of Arts and Sciences and else- 



