PROTOZOA 



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

 cell becomes temporarily an apocyte/ which is then resolved 

 simultaneously into the 1 -nucleate brood-cells. 



A temporary apocytial condition is often passed througli 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-suiDijly of 

 the brood-mother-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, gorged as it were to rei^letion. 

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

 all power of drawing on its ovn\ 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 Ijoth.- We may call this resumjition 

 " germination." 



Very often in the study of a large and complex oi-ganism 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 has gorged itself with them so as to.jiass 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 imder what would outAvardly seem to be most a})propriate conditions. 

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

 that in the Potato the starch can only be digested hj 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 sujjervened ; and that sprouting can only 



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

 Higher Animals, such as Per i2)atus {Yo\. Y. p. 20). It is clearly only a secondary 

 anil derived condition. 



- 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 develoii. This 

 has lieen mistenned "Chemical fertilisation," di.scovered within the last six years 

 1)}' Jacques LoeL. and already the subject of an enormous literature. 



