I 



3 2 PROTOZOA chap. 



completed before the cytoplasm divides ; thus the brood-mother- 

 cell becomes temporarily an apocyte, 1 which is then resolved 

 simultaneously into the 1 -nucleate brood- cells. 



A temporary apocytial condition is often passed through in 

 the formation of the brood of cells by repeated divisions without 

 any interval for enlargement ; for the nuclear divisions may go on 

 more rapidly than those of the cytoplasm, or be completed before 

 any cell-division takes place (Figs. 31, 34, 35, pp. 95, 101, 104), 

 the nuclear process being " accelerated " or the cytoplastic being 

 " retarded," whichever we prefer to say and to hold. Thus as 

 many as thirty-two nuclei may have been formed by repeated 

 binary subdivisions before any division of the cytoplasm takes 

 place to resolve the apocyte into true 1 -nucleate cells. 



In many cases of brood-formation the greater part of the food-supply of 

 the brood-motlier-cell has been stored as reserve-products, which accumulate 

 in quantity in the cell ; this is notably seen in the ovum or egg of the 

 Higher Animals. How great such an accumulation may be is indeed well 

 seen in the enormous yolk of a bird's egg y gorged as it were to repletion. 

 When a cell has entered on such course of " miserly " conduct, it may lose 

 all power of drawing on its own supplies, and finally that of accumulating 

 more, and passes into the state of " rest." To resume activity there is needed 

 either a change in the internal conditions demanding the lapse of time 

 or in the external conditions, or in both. 2 We may call this resumption 

 " germination." 



Very often in the study of a large and complex organism we are able to 

 find processes in action on a large scale which, depending as they must do on 

 the protoplasmic activities of its individual cells, reveal the nature of similar 

 processes in simple unicellular beings : such a clue to the utilisation of 

 reserves by a cell which lias gorged itself with them so as to pass into a state 

 of rest is to be found in that common multicellular organism, the Potato. 

 This stores up reserves in its underground stems (tubers) ; if we plant these 

 immediately on the completion of their growth, they will not start at once, 

 even under what would outwardly seem to be most appropriate conditions. 

 A certain lapse of time is an essential factor for sprouting. It would appear 

 that in the Potato the starch can only be digested by a definite ferment, which 

 does not exist when it is dug, but which is only formed very slowly, and 

 not at all until a certain time has supervened ; and that sprouting can only 



1 This condition may be protracted in the segmentation of the egg of certain 

 Higher Animals, such as Peripatus (Vol. V. p. 20). It is clearly only a secondary 

 and derived condition. 



2 The usual antecedent of change in the condition of the egg is "fertilisation " 

 its conjugation with the sperm ; but this is not invariable ; and a transitory sojourn 

 of certain marine eggs in a liquid containing other substances than sea-water may 

 induce the egg on its return to its native habitat to segment and develop. This 

 has been mistermed "Chemical fertilisation," discovered within the last six years 

 by Jacques Loeb, and already the subject of an enormous literature. 



