43 



theory cannot be justly described as " a very premature 

 and erroneous expression of the real facts. 55 It merely 

 disappoints the expectation raised by Prof. Steenstrup as 

 to its affording an explanation of the facts. And inasmuch 

 as the seed of a plant produces a leaf and its root, which 

 proceeds to develope other leaves before it finally pro- 

 duces the flower with the seed like that from which the 

 first cotyledonal leaf or pair of leaves originated ; and since 

 therefore the plant-individual, in the form of a leaf, inter- 

 venes between the seed and the male and female indivi- 

 duals, called ' stamens and pistils,' concerned in the repro- 

 duction of the seed, the generation of such plant, as Prof. 

 Ed. Forbes has well argued*, may be called ( alternate, 5 

 in the sense in which Steenstrup applies the term to the 

 generation of the Medusa and the Aphis ; and such lan- 

 guage, it seems to me, would be very far from implying 

 " a total misconception of the most important part of the 

 process, 55 though it might not necessarily involve a full and 

 clear recognition of its nature or essential condition. 



The reviewer defines this part of the process to be 

 e growth in continuity with the parent, 5 effecting gemma- 

 tion and also spontaneous fission, in contradistinction to 

 6 multiplication by means of germs detached from the pa- 

 rent. 5 But the nuclear germ-mass in the virgin larviparous 

 Aphis is as really distinct and detached from the parent as 

 the germinal vesicle which is developed into an egg in the 

 wedded oviparous Aphis. In this, when impregnated, a 

 germ-mass must be formed, identical in character with the 

 foregoing, prior to embryonic formation. The first steps 

 of development are identical in both : they might equally 

 be defined as "a multiplication of cells by continuous 

 growth and independent vitality; 55 but this definition 

 would be simply an expression of the well-known fact 

 that cells do multiply, and especially germ-cells, and so 

 produce what may be called e continuous growth, 5 as in 



* Loc. cit. p. 87. 



