192 NATURAL SCIENCE. Sept., 



at the expense of material taken from the outside, and what in one 

 stage is raw material becomes in the next the starting point of the 

 next cell-generation. Thus food-yolk enters the cells, and, though the 

 difference is only quantitative, produces a qualitative change in 

 the embryo. If one thinks of the number of stages between the egg 

 and the adult, and that each stage has had a large absorption and 

 change of foreign material, it gets plain that it is an error to put into 

 the egg all the incipia of adult structures, as many of these come into 

 existence only at later stages of development. 



A second error in the theory of determinants is to attribute to 

 cells — as, for instance, to the ovum and spermatozoon — properties 

 which are not cell properties, but those of combinations of cells. Of 

 the characters of animals and plants, many are due to the co-opera- 

 tion of the whole organism, others to single organs or to groups of 

 cells. If these are to have physical carriers in the germ, are the 

 carriers biophores or determinants ? Hertwig can admit for a cell only 

 characters peculiar to cells. A sexual cell can contain physical 

 incipia for chondrin, ossein, pigment, chlorophyll, nerve fibrillae, but 

 not for the formation of a definite spinal ganglion, a hair, or the 

 biceps muscle. The incipia of these must be groups of cells. 



The egg is an organism which, by feeding, growth, and division, 

 can split up into exactly similar organisms, and it is first through the 

 inter-relations of these new organisms that in each stage of develop- 

 ment the combined organism makes its stages of growth. Criticising 

 the pangenes of De Vries, Weismann says that there cannot 

 be zebra-stripe pangenes, and so forth. There could be black 

 and white pangenes, for these are cell properties ; but the zebra stripe 

 and many similar characters depend not on cells but on the 

 arrangement of cells. Hertwig accuses him of falling into precisely 

 the same error in his determinants. There cannot be in a cell the 

 determinants of organs or structures which depend not on cell 

 characters but upon the relations between cells. 



Thus the human state depends upon the co-operation of many 

 classes of men. Supposing, for the argument, all men to have come 

 from a single pair, this pair, according to Weismann, would contain 

 the determinants of the whole state. But the co-operation of indi- 

 viduals into groups, and of groups into the state, is something new 

 which could not exist while there was only a single pair. Of course 

 the subsequent results are based upon the nature of men, but in no 

 mechanical fashion are they contained in the single pair. So far as 

 causal relations exist between the egg and the organism, the pa-rallel 

 holds exactly. There can be no material particles present in the egg 

 as the incipia of characters due to the co-operation of cells. As 

 Naegeli says, to understand heredity we do not require a separate 

 individual symbol for each difference caused by space, time, and 

 property, but we require a substance which, by the linking of its 

 limited elements, can represent every possible combination of diifer- 



