378 PROVISIONAL HYPOTHESIS Chap. XXVII, 



the tree has its bark and trunk, and certain corals as the 

 Virgularia, have not only parts, but movements in common. 



The existence of free gemmules is a gratuitous assumption, 

 yet can hardly be considered as very improbable, seeing that 

 cells have the power of multiplication through the self-division 

 of their contents. Gemmules differ from true ovules or buds 

 inasmuch as they are supposed to be capable of multiplication 

 in their undeveloped state. No one probably will object to 

 this capacity as improbable. The blastema within the egg has 

 been known to divide and give birth to two embryos; and 

 Thuret 31 has seen the zoospore of an alga divide itself and both 



& 



minate. An atom of small-pox matter, so m 



to be borne by the wind, must multiply itself many thousand- 

 fold in a person thus inoculated. 32 It has recently been ascer- 

 tained 33 that a minute portion of the mucous discharge from an 

 animal affected with rinderpest, if placed in the blood of a 

 healthy ox, increases so fast that in a short space of time " the 

 " whole mass of blood, weighing many pounds, is infected, and 

 " every small particle of that blood contains enough poison to 

 " give, within less than forty-eight hours, the disease to another 

 " animal." 



The retention of free and undeveloped gemmules in the same 

 body from early youth to old age may appear improbable, but 

 we should remember how long seeds lie dormant in the earth 

 and buds in the bark of a tree. Their transmission from genera- 

 tion to generation may appear still more improbable ; but here 

 again we should remember that many rudimentary and useless 

 organs are transmitted and have been transmitted during an 

 indefinite number of generations. We shall presently see how 

 well the long continued transmission of undeveloped gemmules 

 explains many facts. 



As each unit, or group of similar units throughout the body, 

 casts off its gemmules, and as all are contained within the 

 smallest egg or seed, and within each spermatozoon or pollen- 

 grain, their number and minuteness must be something incon- 



31 ' Annal. des Sc. Nat.,' 3rd series, 9th, 1865, pp. 273, 330. 



Bot. torn, xiv., 1850, p. 244. 33 Thivd Eeport of the R# Comm. on 



32 See some very interesting papers the Cattle Plague, as quoted in ' Gard. 

 on this subject by Prof. Lionel Beale, Chronicle,' 1866, p. 446. 



in ' Medical Times and Gazette,' Sept. 





1 



