232 THE INDUCTIONS OF BIOLOGY. 



by uniting with other cells to produce new germs but by pro- 

 ducing new germs without such union. I learn from Dr. 

 Hooker that the Begonia phyllomaniaca habitually develops 

 young plants from the scales of its stem and leaves — nay, 

 that many young plants are developed by a single scale. The 

 epidermal cells composing one of these scales swell, here and 

 there, into large globular cells; form chlorophyll in their 

 interiors; shoot out rudimentary axes; and then, by spon- 

 taneous constrictions, cut themselves off ; drop to the ground ; 

 and grow into Begonias. Moreover, in a succulent English 

 plant, the Malaxis paludosa, a like process occurs: the self- 

 detached cells being, in this case, produced by the surfaces of 

 the leaves.* Thus, there is no warrant for the assump- 



tion that sperm-cells and germ-cells possess powers funda- 

 mentally unlike those of other cells. The inference to which 

 the facts point, is, that they differ from the rest mainly in 

 not having undergone functional adaptations. They are cells 

 which have departed but little from the original and most 

 general type : such specializations as some of them exhibit in 

 the shape of locomotive appliances, being interpretable as ex- 

 trinsic modifications which have reference to nothing beyond 

 certain mechanical requirements. Sundry facts tend 



likewise to show that there does not exist the profound 

 distinction we are apt to assume between the male and 

 female reproductive elements. In the common polype 

 sperm-cells and germ-cells are developed in the same layer of 



* The implication is that an essentially similar process occurs in those 

 fragments of leaves used for artificial propagation. Besides the Begonias 

 in general, I learn that various other plants are thus multiplied — Citron 

 and orange trees, Hoya carnosUy Aucvha japonica, Clmnilms punicenis^ 

 etc., etc. BryophyUum calicinum, Jiochea falcata, and Echevei'm. I also 

 learn that the following plants, among others, produce buds from their 

 foliage leaves: — Cardamine pratensh, Nasturtium qfflcmale, Roripa palvs- 

 tris, Brassica olcracea, Arahis pumila, CheUdonium majris, Kymphoea guianen- 

 sis, Episcia bicolor, Chirita sivensis, Pinguicula Backcri, Allium^ Gagea, 

 Tolmia, Eriiillaria, Ornithogahim, etc. In Cardamine and several others, a 

 complete miniature plant is at once produced ; in other cases bulbils or simi- 

 lar detachable buds. 



