ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 701 



new Zeiss ^ apocliromat made in 1910. He tested it upon diatomic 

 structures, although the lens had not been specially constructed for such 

 work. In several cases doubtful features were completely established ; 

 in others new features were revealed. Among the instances he <nves are 

 the following : — 



Craspedodiscus coscinodiscus. — Secondaries previously doubtful, now 

 clearly exhibited. 



Epithemia turgida. — Primaries prove to be irregularly cruciform in 

 shape, somewhat of the arachnodiscas type. High magnification (3000) 

 required. 



Cymbella gastroides Kiitz. — Primaries rectangular in shape, divided 

 and broken up into secondaries. 



Gomphonema geminatum Ag. — Secondaries closely resembling the 

 foregoing. 



Stictodiscus areolatus Grun (Oamaru). — Exhibits a delicate but not 

 particularly difficult network on the lower surface of the valve. A fine 

 dotted structure can be seen on the under edge of the rim. 



Aulacodiscus Janischii Gr. and St. (Oamaru). — Exhibits a very dis- 

 tinct and obvious veil. Should prove to be within the grasp of most 

 good cheap oil-immersion lenses. 



Eudktia oceanica Ehr. (fossil, from Peru guano). — Possesses easy 

 secondary perforations plainly seen in balsam. 



All the foregoing observations were made with working apertures 

 varying between 1*3 and - 95 N.A. In no instance was oblique light 

 or a smaller illuminating cone employed. 



The Micrologist.*— This quarterly journal, edited by A. Flatters, 

 made its first appearance in July 1910. Its aims are to instruct the 

 amateur microscopist in the methods of preparing and mounting natural 

 history specimens for microscopical examination. It is illustrated by 

 photomicrographs and also by ordinary line or half-tone blocks. The first 

 volume contains manipulative methods necessary for microscopical work, 

 and in the future special types will be taken, selections being made from 

 those not generally dealt with in ordinary text-books. The first five 

 numbers more than bear out the intention of the editor : they are full 

 of practical information and are most excellently illustrated. The price 

 is very moderate. 



Principal Starches used as Food.f — This work by Waldron Griffiths 

 has passed into a second edition. Its general characters are unaltered, 

 but the number of illustrations has been considerably increased and the 

 short descriptions have been as far as possible brought up to date. The 

 object of the work is to facilitate the identification of starch, especially 

 when used either for purposes of adulteration or substitution ; it cer- 

 tainly fulfils the intention of the author. 



Gleichen, A. — Die Theorien der modernen optischen Instrumente. 



Stuttgart : P. Enke (1911) 332 pp. 



* Manchester: Flatters, Milborne, and M'Kechnie, Ltd., 1910-11, pts. i.-v. 

 t Cirencester : Baily and Woods (1911) 2nd ed. 70 pp. (38 figs.). 



Oct. 18th, 1911 -1 Z 



