TABLE IV. 



Systematic Survey of the five earliest germinal stages of Animals witl) 

 reference to the four different type-forms of Egg-cleavage. 



a. Orif^inal or primor- 

 dial cleavage. 



A. Total Cleavage. 



(^Segmentatio totalis.) 



A, 



I. a. Archi- 



monerula. 



(Fig. 22^, p. 191.) 



A cytod in which 



the formative and 



nutritive yelk are not 



distinct. 



n. a. Archi- 

 cytula. 



(Plate II. Fig. 1.) 

 Parent-cell which 

 h;is arisen out of the 

 archi-monerula by the 

 formation of the pa- 

 rent-kernel. 



III. a. Archi- 



mornla. 

 (Plate II. Fig. 3.) 

 A solid (generally 



globular) heap of 



similar cells. 



IV. a. Archi- 



blastula. 

 (Plate II. Fig. 4.) 

 A hollow (usually 

 globular) vesicle, the 

 wall of which consists 

 of a single layer of 

 similar cells. 



v. a. Archi- 



gastrula. 

 Bell-gastrula. 



?'late II. Fig. 6.) 

 ig. 23-28, p. 193. 

 Primitive intestine 

 empty, without nu- 

 tritive yelk. Pri- 

 mary germ - layers 

 »ne-layered. 



I- &. Amphi- 

 moneruia. 



A cytod which 

 includes fonnative 

 yelk at the animal 

 pole, nutritive yelk 

 at the vegetative 

 pole : the two are 

 not very distinct. 



II. 6. Amphi- 

 cytula. 



(Plate II. Fig. 7, 12.) 



Parent-cell which 

 has arisen out of the 

 amphi-monerula by 

 the formation of the 

 parent-kernel. 



III. 5. Amphi- 

 morula. 



(Plate II. Fig. 9.) 

 A roundish heap 

 formed of two kinds 

 of cells, the animal 

 cells at one, the vege- 

 tative cells at the 

 other pole. 



IV. 6. Amphi- 



blastula. 

 (Plate II. Fig. 10.) 

 A roundish vesicle, 

 the wall of which at 

 the animal pole con- 

 si.-ts of smaller cells, 

 at the vegetative 

 pole of larger cells. 



V. 6. Amphi- 

 gastrula. 



Hood-gastnila. 



(Plate II. Fig. 11,17.) 



Fig. 32-35, p. 206, 



Fig. 41. 



Primitive intestine 



partly filled with 



segmented nutritive 



yelk. Germ-laj-ers 



often many-layered. 



B. Partial Cleavage. 



(^Segmentatio partialis.) 



c. Discoidal cleavage. 



I. c. Disco- 

 monerula, 

 A cytod which 

 includes formative 

 yelk at the animal 

 pole, nutritive j'elk 

 at the \egetative 

 pole : the two are 

 quite distinct. 



II. c. Disco- 



cytula. 



(Plate III. Fig. 18.) 



Parent-cell which 

 has arisen out of the 

 disco-monerula by 

 the formation of the 

 parent-kernel. 



III. c. Disco- 

 morula. 

 (Plate III. Fig. 21.) 

 A flat disc, com- 

 posed of similar cells 

 on the animal pole 

 of nutritive yelk. 



IV. c. Disco- 

 blastula. 



(Plate III. Fig. 22.) 

 A roundish ve-^sicle, 

 the small hemisphere 

 of which consists of 

 cleavage - cells, the 

 larger of nutritive 

 yelk. 



V. c. Disco- 

 gastruia. 



Disc-ga>trula. 



(Plate III. Fig. 24.) 



Fig. 43, p. 219, 



Fig. 49, p. 228. 



Primitive intestine 

 filled with unscg- 

 meiitcd nutritive 

 yelk. Flat germ-disc. 



d. Superficial cleavage. 



I. d. Peri- 

 monerula. 

 A cytod which in- 

 cludes formative yelk 

 in the outer wall, 

 nutritive yelk in the 

 centre. 



II. d. Peri- 



cytula. 



(Plate III. Fig. 25.) 



Parent-cell which 

 has arisen out of the 

 peri-monerula by the 

 formation of the pa- 

 rent-kernel. 



III. d. Peri- 



morula. 



(Plate III. Fig. 27.) 



A closed vesicle : a 

 cellular stratum sur- 

 rounds the w hole cen- 

 tral nutritive yelk. 



IV. d. Peri- 



blastula. 



(Plate III. Fig. 28.) 



A closed vesicle : a 

 cell layer surrounds 

 the whole nutriiive 

 yelk (= Peri-morula). 



V. d. Peri- 



gastrula 



Bladdcr-gastrula. 



(Plate III. Fig. 29.) 



Cleavage-cavity fiU- 

 ed with unsegmented 

 nutritive yelk. Pri- 

 mitive intestine dil' 

 ferent. 



