152 



THE AMERICAN MONTHLY 



[August, 



thickness. The author distinguishes 

 the male and female frustules by their 

 size and manner of growth, the 

 former being small (.001^6 inch in 

 length), delicate, with a relatively 

 small amount of endochrome, which 

 is arranged about the nucleus in a 

 roughly stellate manner. These frus- 

 tules, attached by their corners, grow 

 in a zigzag chain. 



The female frustules ai"e but slightly 

 larger (.001S8 inch), but are distin- 

 guislied by numerous annuli and a 

 large hoop in the middle. 



In conjugation the male frustules 

 attach themselves to the female, at or 

 near the free end of a filament ; usu- 

 ally four males are found on one 

 female, but as many as eight have 

 been observed. It would appear that 

 the male filament breaks up and the 

 individual frustules make their way 

 to the female, and there attach them- 

 selves by their corners. 



It now appears that the terminal 

 half of the female frustule falls away, 

 leaving the cell open. A gelatinous 

 secretion closes it again. In some 

 way, not very clearly explained in the 

 article, the contents of the male frus- 

 tule pass into the female cell. Being 

 thus fertilized, the contents become 

 suiTounded with a thick, gelatinous 

 secretion and form a large sporangium 

 outside of the frustule. Either one 

 or two sporangia may be formed from 

 a single frustule. It is suggested that 

 if the nucleus has divided just before 

 fertilization there will be two sporan- 

 gia, otherwise only one. 



Within the clear sporangium a new 

 frustule is produced, about three 

 times the length of the original female 

 cell. 



The conjugation of diatoms is a 

 process deserving of very careful 

 study, and there is no field of oliser- 

 vation open to the general student of 

 microscojiic life that promises better 

 opportunities for new discoveries of 

 importance. IMie subject is still very 

 imperfectly understood. If the many 

 who spend their time in detecting 

 slight diflerences in form and mark- 



ings of the frustules, thereby discrim- 

 inating ephemeral species, and adding 

 to the already almost inextricable con- 

 fusion in the classification of the dia- 

 toms, would devote their spare mo- 

 ments to the study of the phenomena 

 of the life, growth, and reproduction 

 of these organisms, the results would 

 be of great value to science. Will 

 not some of our readers who are look-, 

 ing for a field of original work take 

 up this subject in earnest ? The speci- 

 mens can be collected, preserved, and 

 mounted, and then studied at leisure. 



Staining Tissues in Microscopy.* 

 IV. 



BY PROF. HANS GIERKE. 



[ Continued from f. /JJ.] 

 ANILIN DYES. 



71. Beneke, Correspbl. d. Vereins f. 



gemeinschaftl. Arbeiten, 

 1862. No. 59, p. 980. 

 Recommends dissolving commer- 

 cial lilac anilin in acetic acid, which 

 gives a clear solution. 



72. Waldeyer. (See No. 36.) Un- 



tersuchungen u. s. w. in Henle 

 u. Pfeufer's Zeitschr. 3 Reihe, 

 Bd. XX, p. 200. 1863. 

 Describes a course of experiments 

 with anilin dyes, especially red. vio- 

 let, and Paris blue. The red is par- 

 ticularly commended. A strong solu- 

 tion contains, in 50 c. c. of water, 15 

 drops commercial anilin red, a weaker 

 has 25o-3C)o_c. c. more water. This 

 dye stains more quickly than am- 

 moniacal carmine. It will even color 

 in an instant under the cover-glass. 

 But the preparations darken and are 

 not permanent. Nuclei take the color 

 more readily than protoplasm, and the 

 axis cylinder more readily than the 

 medullar\' substance of nerves. 



73. Onimus. De I'emploi de la fuch- 



sin dans I'etude des elements 

 anatomiques. Jour. deTAnat., 

 1865. No. V, p. 569. 

 Recommends fuchsin as a stain. 



*From the Zeitschri/t/tirwisstnschaftlicheMikros- 

 kopie. Translated for this JoUKNAL by Prof. Wm, H, 

 Seaman, M D. 



