228 



SCIENCE. 



[N. S. Vol. XII. No. 293. 



Society Montreal, most of which were obtained 

 in Canada. Two species of the genus Euthamia, 

 E. graminifolia, the bushy goldenrod, and E. 

 Caroliniana, a slender fragrant goldenrod, were 

 added. A review of Dr. Whiteaves's paper on 

 the 'Devonian System in Canada,' by Dr. H. 

 M. Ami, and one on ' Dr. A. B. Barlow's re- 

 port on the geology and natural resources of 

 the Lake Nipissing and Lake Temiscaming dis- 

 trict of Ontario and adjoining portions of Que- 

 bec,' by Dr. F. D. Adams are then given. 

 These are followed by a review of Mr. Lambe's 

 ' contributions ' to Canadian paleontology. Vol. 

 4, Pt. 1, on paleozoic corals, by Dr. F. D. 

 Adams, and a synopsis of the annual report of 

 the Geological Survey of Canada, Vol. 10, by 

 Dr. H. M. Ami. The volume concludes with ■ 

 the abstracts of meteorological observations 

 taken at McGill College Observatory, Montreal, 

 for the year 1899. 



. SOCIETIES AND ACADEMIES. 



ZOOLOGICAL CLUB, UNIVERSITY OF CHICAGO. 

 MEETINGS OP THE SPRING QUARTER, 1900. 



At the first meeting of the quarter, April 

 11th, Professor C. B. Davenport read a paper 

 entitled ' Variation in Pectinella ' giving the 

 results of a statistical study of the spines of 

 the statoblasts. An abstract of this paper has 

 appeared in an earlier number of Science. 

 The session of April 25th was devoted to a 

 paper by Dr. C. M. Child on ' Abnormalities in 

 Cestodes.' The abnormalities described were 

 selected from a number of specimens of the 

 sheep tape-worm Moniezia expansa, most of 

 them occurring in a single specimen in which 

 over a hundred abnormal proglottids were 

 found. The proglottids of this species are very 

 short and wide with a set of genital organs and 

 a pore on each side. The variations range 

 from the simple incomplete separation of pro- 

 glottids to long spiral proglottids, making seven 

 turns about the body. In many cases very dif- 

 ferent form-relations occur upon the dorsal and 

 ventral surfaces. The most interesting point 

 in connection with the abnormal segments is 

 the structure of their genital organs. All the 

 organs show a very distinct correlation in form 

 and structure with the form of the proglottid. 



i. e., a high degree of adaptation. In the in- 

 completely separated segments, conditions are 

 found ranging from the normal, with two com- 

 plete sets of organs in each segment, through 

 forms where the pores of two proglottids are 

 approximated, or the ducts of two sets of 

 organs are united and open through a common 

 pore, to forms in which a proglottid of nearly 

 double the normal length contains only one set 

 of organs on each side, the difl'erent conditions 

 being the result of differing degrees of union 

 between the segments. So close is the corre- 

 spondence between the form of the proglottid 

 and the structure of the contained organs that, 

 in cases where the form- relations are not alike 

 on dorsal and ventral slides, the genital organs 

 of the dorsal side (vas deferens, vagina and 

 testes) correspond in position with the form- 

 relations of the dorsal side, while the organs 

 situated ventrally (ovary, vitellarium and sem- 

 inal receptacle) conform to the relations on the 

 ventral side. 



In general each particular portion of the 

 genital organs tends to occupy as nearly as 

 possible its normal position with respect to the 

 boundaries of the proglottid in its immediate 

 vicinity. Abnormal form of the proglottid thus 

 causes abnormal position and form in the genital 

 organs, this being sometimes so great as to pre- 

 vent the organs from being functional. 



On May 9th, at the third session of the Club, 

 Mr. E. R. Downing read a paper entitled ' The 

 Spermatogenesis of Hydra,' giving the results 

 of his study of this form. 



The principal points of Mr. Downing's paper 

 are as follows : The somatic cells divide ami- 

 totically usually, probably always. The sperm- 

 atogonia arise by amitotic division from the 

 interstitial cells and from the ectoderm cells. 

 They divide mitotically to form the spermato- 

 cytes of which there is a single generation. 

 These form the spermatids by mitosis. Pre- 

 ceding each mitotic division the nucleus and 

 cell both increase in size, especially the former. 

 After division the daughter cells become cor- 

 respondingly smaller. The spermatocytes and 

 spermatids contain six chromosomes, the sperm- 

 atogonia twelve. In the prophase of mitosis 

 the nuclear reticulum becomes more coarsely 

 meshed, and the chromatin gathers into a num- 



