OF THE PHYTOZOA. 179 



instead of which are seen two granules; the primordial ceUs are in im- 

 mediate contact at the sides, and are of an oval or globular shape ; their 

 common enyeloping membrane is at first constricted at the border following 

 the outHne of the primordial cells ; it eventually becomes globular, although 

 continiung for a long time much flattened at the poles, in the form of a disk- 

 shaped spheroid. When the Chlamydococcus-like unicellular Sfej^hanosjyJicera 

 has commenced its division early in the evening, the di\'ision into eight is 

 perfected during the night, and early in the morning the young family quits 

 its cast-off mother-cell membrane. 



" In the course of the day the individual primordial cells, and their common 

 enveloping membrane, grow until the latter attains a diameter of 0-040- 

 0-048'". Dming this growth the shape of the primordial cells is changed 

 by the formation of various prolongations in the manner above described : 

 but in the coiu'se of the afternoon the primorchal cells again become round ; 

 and during the evening, division commences in them precisely similar to the 

 process in the imicellular Stephanosphceixi : on the follo^dng morning we 

 find eight young families, with the common enveloping membrane, which 

 soon escape and go through the same process. It is calculated that in eight 

 days, imder favoiu^able circumstances, 16,777,216 families may be formed 

 from one resting-ceU of StepTianospli(xra. It is remarkable that the division 

 of the primordial ceUs in Steplianospluera is confined to a certain time of day : 

 it begins towards evening, and is completed the following morning. In the 

 observations made in Laj)land, at a time when the daylight there lasted diuing 

 the whole night, the beginning and end of the division were observed to take 

 place at almost the same hours as in the observations made at Breslau m the 

 spring, when the day and night were almost of equal length. Sometimes 

 the division ceases after the formation of only four primordial cells. On one 

 occasion the authors observed a family with only three cells, one only of 

 the two halves first formed having undergone a second division. In Lap- 

 land a family with sixteen cells was once observed. 



'' The authors then proceed to discuss the natiu-e of the resting-cells in 

 Stephanosjjhcera and CliJamydococcus, and come to the conclusion that they 

 are not spores ; i. e. that they are not of the same nature as the red cells of 

 (Edogonium, BulhocJicete, Draparnaldia, CJicetopJiora , Sphceroplea , Volvocc, &c. 



" They come to this conclusion upon two grounds : 1st, that the resting- 

 ceUs in question continue to grow after becoming quiescent ; and secondly, 

 that it is probable (although not yet proved) that the resting-ceUs increase 

 by self-division, thus producing new generations of resting- cells. These two 

 characteristics the authors consider inconsistent with the idea of a spore. 



'' In conclusion, the authors notice the formation of microgonidia in Steplia- 

 nosplicera, which takes place by the division of the primordial cells into num- 

 berless small portions. Fig. 5 shows a Stephanosphcera, in which seven of the 

 eight primordial cells have formed microgonidia ; the individual microgonidia 

 (fig. 52 a, h, c) become free by the disintegration of these eight groups into 

 their constituent portions. The authors think it not improbable that the 

 microgonidia exercise an impregnative influence in spore -formation, but admit 

 that there is no evidence to prove it." 



Mr. Currey (J. M. S. 1858, p. 209) reopens the question concerning the 

 natui^e of the red resting-cells of StephanospJicera, and argues against the 

 conclusion drawn by Cohn and Wichura. He says those observers have 

 noticed '' that these cells in Step}ianosp}i<r.ra pluvialis, which are at first of a 

 green colour, and furnished with cilia, increase in growth after the green 

 colour and the cilia have disappeared, i. e. after they have assumed a state of 

 rest, a fact which they consider to militate against their character as spores. 



x2 



