72 COCCOPHYCE^;. 



parent globe. This process was observed to occupy about twelve hours. 

 Cohn also observed the division of each of the eight primordial cells into 

 a great number of microgonidia, which swarm within the globe, and 

 escape from it. Under certain circumstances each of the eight cells 

 secretes a cellular covering, and swims about in the interior of the 

 globe in the form of free Chlamydococcus-like cells. Eventually they 

 escape either by fissure of the globe or by its gradual dissolution, lose 

 their cilia, form a thicker membrane, become motionless, and accumu- 

 late at the bottom of the vessel. If the vessel be permitted to become 

 dry, and afterwards filled with water, motile Stephanospheera reappear, 

 from which it seems probable that the green globes are the resting cells. 



The resting cells vary much in size, and it is supposed that they 

 grow considerably after attaining a state of rest. The colour is deep 

 green, sometimes yellowish or olive, and they possess a nucleus. 



The dried resting spores absorb water, and their contents gradually 

 fill up the cavity of the containing membrane, and become cloudy and 

 granular ; the border becomes yellowish, and the red colouring matter is 

 contracted in the centre. The cells then begin to divide and pass 

 through successive stages, as shown on the plate (Plate 28, figs. 13 

 to 17). The four daughter-cells begin to quiver, and endeavour to 

 separate from each other. Two cilia are now apparent at the pointed 

 extremity of each of the four cells (fig. 19), by the action of which the 

 group begins to move as a whole ; utlimately all trace of the enveloping 

 membrane disappears, and one by one the daughter-cells escape and 

 become free. At the moment of escape their diameter never exceeds 

 01 mm., but they soon enlarge to a diameter of '013 to *015 mm. 



The length of time which elapsed between the immersion of the 

 dried resting spores and the first appearance of the motile cells varied 

 from nine to twenty-four hours. It was observed that those resting 

 spores which did not produce zoospores within six days never did so 

 afterwards, although they continued to live, and seemed perfectly 

 healthy. Zoospores produced in November did not advance beyond the 

 first stage. Others produced in March remained only a few hours in 

 that condition, after which time a delicate membrane was formed 

 round the body of the primordial cell ; this membrane was at first 

 closely attached to the cell, but became gradually enlarged, by absorp- 

 tion of water, into a colourless enveloping vesicle, usually globular, 

 but sometimes oval, having two openings, through which the cilia 

 penetrate. In this condition they attain a diameter of '017 to '022 mm., 

 and are not distinguishable from encysted forms of Chlamydococcus 

 pluvialis. Other zoospores, produced in April, attained a larger size, 

 and the protoplasm of the primordial cell, instead of retaining its con- 

 tinuous outline, became elongated here and there into simple or forked 

 mucilaginous rays, which were either colourless or green from the presence 

 of chlorophyll. These rays are probably produced by the protoplasm ad- 

 hering at certain points to the surrounding membrane, and being carried 

 outwards by its growth. The Chlamydococcus like form only lastei a 

 few hours ; towards the evening the zoospores mostly began to divide. 

 The rays are drawn in, the primordial cell becomes round, it then elon- 

 gates, is constricted, and ultimately is divided into four quadrants. 

 These are again bisected, and eventually eight wedge-shaped portions are 

 formed, whose contour lines, like the spokes of a wheel, meet in the 

 middle. 



Here is to be noted a distinction between the Stej}hanosj)h(?ra and 

 Chlamydococcus; for while in the latter the individual portion^ of a 

 primordial cell separate entirely from each other, each developing its own 

 enveloping membrane, and ultimately escaping as a unicellular indi- 

 vidual, in the former the eight portions remain united as a family. The 



