ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
285 
Observation of the Process of Fecundation.* — M. L. Guignard 
recommends the following method of preparation for observing the 
various stages in the process of fecundation, whether of animals or plants, 
especially the part played by the “ directing spheres.” The best fixing 
material is absolute alcohol, either pure or with the addition of from 0‘2 
to 0 • 3 per cent, of corrosive sublimate or picric acid. A 1 per cent, 
aqueous solution of sublimate, a saturated solution of picric acid, and a 
0 • 5 per cent, solution of chromic acid, also give good results. In treating 
the cells themselves with vapour of osmic acid, it is necessary to note 
the exact time necessary and sufficient for complete fixation, too long 
exposure injures the staining. The preparation may then be hardened, 
first with Flemming’s fluid, then with absolute alcohol. Flemming’s 
fluid does not answer so well with tissues which arc to be fixed en masse , 
such as pollen-cells or ovules, as with the contents of the embryo-sac 
extracted from the ovule after fecundation. The best staining reagent 
for the “ directing spheres ” is hsematoxylin. 
Study of Spermatogenesis.! — Dr. C. Pictet recommends three modes 
of procedure in the investigation of the delicate seminal cells — exami- 
nation of living cells, various modes of dissociation and examination in 
more or less indifferent fluids, and sections. The last, however, is of 
little use. Examination of the living cell is most important, as there is 
no known reagent that does not alter it. The nucleus has generally 
been studied in a solution (1 per cent, to 3 per cent.) of acetic acid iu 
water ; dahlia (St. George’s formula) or metliyl-green (Carnoy) have 
been almost exclusively used as staining reagents. Good preparations 
havo been obtained by the vapour of osmic acid, followed by pyrogallie 
acid ; and by chloride of platinum and permanganate of potash. It 
must be remembered that the accessory nucleus is destroyed by acetic 
acid ; when that body is to be retained, it is advisablo to use a watery 
solution (5 per cent, to 10 per cent.) of chloride of manganese, to which a 
few drops of a concentrated aqueous solution of dahlia havo been added ; 
this reagent is strongly recommended by the author. 
Study of Development of Oviduct of Frog.| — Mr. E. W. MacBride 
prepared his tadpoles either with corrosive sublimate or with Perenyi’s 
fluid and alcohol. Decalcification was effected by nitric acid in strengths 
varying from 1 to 10 per cent. ; strange to say, no difference was 
observed with different strengths, but a 3 per cent, solution for twenty- 
four hours may be recommended. Material preserved in picric acid was 
found to be quite unsuitable. The method of study was solely that of 
a series of transverse sections, but it is well to first remove the greater 
part of the gut, almost all the liver, the heart, and most of the lungs. 
Study of Neomenians.§ — M. G. Pruvot found that the best fixing 
reagent was corrosive sublimate concentrated at freezing-point; colora- 
tion en masse was very well effected in three or four hours by alum- 
carmine. Double staining, after sectionizing, by a watery solution of 
hmmatoxylin and eosin gave very fine prejrarations ; it has the advantage 
^ * Ann. Sci. Nat. (Bot.), xiv. (1891) pp. 166-9. 
t Mittheil. Zool. Stat. Neapel, x. (1891) p. 75. 
t Quart. Journ. Micr. Sci., xxxiii. (1892) pp. 273-4. 
§ Arch. Zool. Expe'r. et Gen., ix. (1891) pp. 701-2. 
1892. 
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