588 PEOFESSOR MARCUS HAETOG. 



henceforwai'd is in favour of the view that in the animal, as 

 in the plant, a cell can only utilise its reserves secondarily 

 and mediately — by the internal secretion of an enzyme. We 

 have here to note that the distinction of metabolic processes 

 into the two well-known categories of ''anabolic'^ and 

 "catabolic^' is inadequate, for anabolism is not uniform, 

 but twofold. 



A cell like the ovarian ovum, receiving dissolved nutriment, 

 builds it up in two modes, in sharp contrast with one another : 

 (1) into protoplasmic matter, inducing protoplasmic growth; 

 and (2) into food material. The not uncommon assumption 

 that the original formation of reserves is due to the partial 

 breakdown of living protoplasmic substance has, so far as I 

 know, not a spark of evidence to warrant it. We have there- 

 fore to distinguish {a) ^^plasmic anabolism," resulting in 

 growth, and {b) "reserve anabolism," which means the 

 enlargement of a cell through the accumulation of inert pro- 

 ducts. Such a cell, gorged with inert matter, has not the 

 same need for a corresponding increase of surface as a cell 

 whose protoplasm has enlarged ; and consequently it does not 

 divide. If, however, this cell begins to form an internal 

 enzyme, it can utilise its reserves : its protoplasm grows at 

 the expense of these reserves, and responds to the need of 

 increased surface by dividing. The daughter-cells repeat the 

 same performance till the reserves are utilised. Thus we 

 have the process of brood-formation (" multiple cell-formation," 

 " sporulation," " segmentation "), which stands at first sight in 

 such strong contrast to Spencer's binary cell division at the 

 limit of growth, brought under the same general laws therewith. 



The segmenting oosperm is as strongly anabolic as the 

 ovarian egg, but in a different Avay. To deny its anabolic 

 character because of the necessary antecedent catabolic 

 hydrolysis of its reserves would warrant one in regarding a 

 growing child as mainly catabolic in character because it has 

 to digest its mother's milk, or the pap supplied by its nurse. 

 The confusion of ideas due to the non-recognition of this 

 distinction of the two forms of anabolism has been responsible 



