104 



SCIENCE. 



[N. S. Vol. VII. No. 160. 



i;lie calculus have plucked Williamson and Tod- 

 hunter and each other, I recommend a raid on 

 Perry by way of refreshing variety. 



Having got his reader fairly into the calculus, 

 "the author finally confesses a weakness for the 

 subject and adds a third chapter of ' academic 

 exercises,' in which he treats the subject of the 

 usual text-books, only in a different order and 

 briefly, but nevertheless including differential 

 equations, Bessel's functions and spherical har- 

 monics. 



Even the student who has already studied 

 •the calculus in the usual systematic form will 

 profit by traversing it with the author; and to 

 the engineer the book must be very useful. 

 The lecture style in which it is written often 

 makes the subject more attractive. It also 

 -sometimes carries away the author, in an excess 

 -of enthusiasm, into expressions of opinion 

 which are not to be taken too seriously nor yet 

 to be 'skipped,' as the author advises in the 

 cases of difficult passages. 



F. N. Cole. 



Columbia University. 



SOCIETIES AND ACADEMIES. 



ZOOLOGICAX CLUB, UNIVERSITY OF CHICAC40, 

 NOVEMBEB, 1H97. 



A Neiv Human Txnia {Tsenia confusa, Wai-d). 

 — The new form has much of the slender ap- 

 pearance and delicate structure of Tsenia solium, 

 but as regards the size of the proglottids is 

 even larger than Teenia saginata. The segments 

 are of almost uniform breadth and very narrow. 

 In addition to a peculiarly constructed head, 

 the worm presents many variations of bodily 

 structure when compared with the ordinary 

 forms. The sexually mature proglottids meas- 

 ure 4-5 mm. long by 3-4.5 mm. wide ; the lobes 

 -of the ovai-y are kidney-shaped and two or 

 three times as long as broad ; the genital pore 

 is extremely shallow ; in all of which respects it 

 differs markedly from either T. saginata or T. 

 solium. A short distance from the exterior the 

 vagina is provided with a very distinct sphinc- 

 ter muscle. A similar structure was found also 

 in preparations of T. saginata. Such a muscle, 

 heretofore, was thought to exist only in 

 other than human Tsenise. Just before the 

 vagina reaches the receptaculum seminis it be- 



comes highly modified and, unlike that of T 

 saginata or T. solium, is encircled by a number 

 of small sphincter muscles. As regards the 

 male reproductive system, the testes are smaller 

 than those of T. saginata, and a distinct seminal 

 vesicle is present. The terminal or ripe prog- 

 lottids are of an extreme length, measur- 

 ing 28-35 mm. long by only 4-5 mm. wide. 

 They never have the peculiar pumpkin-seed 

 shape so characteristic of T. saginata, but are 

 of constant transverse diameter, flaring slightly 

 at the posterior end to form a broad base of at- 

 tachment for the succeeding proglottid. The 

 branches of the uterus number from 11 to 14, and 

 are divided more or less arborescently, resem- 

 bling those of T. soZjMm somewhat in general con- 

 figuration. The eggs are without pyriform ap- 

 paratus and measure about 30 by 39 micra. 

 The longitudinal nerves run in strands of from 

 three to five down each side of the body ; near 

 the pore the strands separate, part going ven- 

 tral and part dorsal to the genital ducts. The 

 longitudinal muscles are continuous throughout 

 the body. 



M. F. GUYEE. 



Some Features of the Oogenesis of Sternaspis. 

 — The egg-cells arise in the manner described 

 by Vejdovsky from the peritoneal epithelium of 

 certain blood-vessels, forming a single pair of 

 distinct ovaries, each surrounded by a fold of 

 the peritoneum and opening to the exterior of 

 a distinct oviduct. 



As the egg-cell grows a pedicle is formed be- 

 neath it, and in this appears a loop of the blood- 

 vessel as described by Vejdovsky. The end of 

 the loop enters the egg-cell. 



In early stages the egg-cell contains a large 

 nucleus with prominent nucleolus and reticular 

 cytoplasm. As growth proceeds the cytoplasm 

 begins to assume a radiating structure, center- 

 ing about the end of the vascular loop. The 

 first yolk-granules deposited appear in the por- 

 tions of the egg farthest from the point of 

 attachment. The radiate arrangement of the 

 cytoplasm becomes more distinct as yolk is 

 formed, and the region immediately surround- 

 ing the vascular loop stains very deeply. 



The egg is now pear-shaped, hanging from its 

 stalk with the nucleus in the broader end sur- 



