1704 Journal of Applied Microscopy 



Stevens, F. L. Gametogenesis and Fertiliza- The Striking dififerences presented by 



tion in Albugo. Contributions from the ^, ... . . ,, r,,-,- j ^ 



Hull Botanical Laboratory XXIX. Botanical the conditions in Albugo Bhft ^nd A. 



Gazette, 32: 77-9S, 157-169, 238-261, pis. Candida induced Prof. Stevens to make 



'~'^' ^^ ■ a comparative study of the genus. All 



material was fixed in chromo-acetic acid and stained in Flemming's safranin- 



gentian violet-orange combination. Albugo Portulaccte and A. Tragopogonis were 



thoroughly studied, and A. Candida was again reexamined. The principal 



results are as follows : 



In A. ForfulacccB and in A. Tragopogonis a multinucleate oosphere develops as 

 in A. Bliti. In both forms two mitroses occur in oogenesis and in spermato- 

 genesis, the nuclear figure of the second mitosis being clearly distinguished from 

 that of the first by its diminished kinoplasm. In A. Fortulacae the antheridial 

 tube is multinucleate and the numerous antheridial nuclei fuse in pairs with the 

 numerous ^^g nuclei. In A. Tragopogonis the multinucleate oosphere becomes 

 reduced to the uninucleate condition by the disorganization of the supernumer- 

 ary nuclei, after which the antheridial tube conveys one or more nuclei into the 

 oosphere, where one antheridial nucleus fuses with the egg nucleus. VdA. Por- 

 tulaccce the fusion nuclei pass the winter without further change, while in A. 

 Tragoporgonis the fusion nucleus divides repeatedly, consequently giving rise to 

 a multinucleate winter oospore. The supernumerary nuclei are phylogenetically 

 gametes, which degenerate as in the Fucacece and some other forms. The four 

 species, A. Fortulacae, A. Bliti, A. Tragopogonis and A. Candida constitute a 

 series in which the coenocentrum increases in complexity, the receptive papilla 

 decreases, and the number of functional nuclei decreases. Of these A. Fortu- 

 lacccB is probably the most primative form. The relation between Albugo, Fer- 

 onospora and Saprolegnia is emphasized by their cytology and all are probably 

 derived from a common ancester having a multinucleate oosphere. If the Phycomy- 

 cetes are related to Vauchcria it is from a period before the attainment of the 

 uninucleate oosphere by Vaucheria. c. j. C. 



Hinze, Q. Ueber den Bau der Zellen von ^<- As far as possible, the cells were Stud- 

 giatoa fniraNlis Cohn. Ber. d. deutsch. bot. ied in the living condition, but for the 



Gesell. 19: 369-373, pi. iS, 1901. ^ j ^ -i • i. 



o ^ o/j. 1 . y finer details microtome sections were 



made from material fixed in Flemming's solution and stained in Heidenhain's 

 iron-alum-haematoxylin. The cells are surrounded by a double wall. The proto- 

 plasm, as in the higher plants, forms a layer inside the membrane and contains 

 vacuoles filled with cell sap. No differentiation into an outer protoplasmic layer 

 and a central body could be demonstrated. There is no nucleus. The trans- 

 verse walls give no cellulose reaction, but, on the contrary, stain with ruthenium 

 red, safranin and methyl blue. It is worthy of note that the cells are not plas- 

 molyzed by solutions of saltpeter, sugar, and glycerine. When a contraction of 

 the plasma body is produced, either the entire membrane collapses with it or 

 only the inner layer of the membrane remains in connection with the plasma 

 body. After the sulphur has been dissolved out with absolute alcohol, there still 

 remain bodies which stain with haematoxylin. These the writer regards as chro-. 

 matin granules. Besides the chromatin granules, there is also a substance which 

 is apparently a carbohydrate nearly related to starch. 



In cell division the transverse wall first appears as a ring on the inner sur- 

 face of the cell membrane. This then grows toward the center of the cell as in 

 Spirogyra. The formation of the transverse walls can be observed in living cells, 

 but preparations deeply stained with haematoxylin are more favorable, c. j. c. 



