Maech 29, 1907] 



SCIENCE 



489 



would require. In other organs, especially 

 in those with an internal secretion, the 

 margin of safety amounts sometimes to ten 

 or fifteen times the amount of the actual 

 need. An extreme degree of superabun- 

 dance and actual wastefulness we meet 

 with in the organs and functions having 

 charge of the continuation of the species. 

 Let us illustrate it by the following few 

 data. The ovum exists for the purpose of 

 reproduction. Assuming that the sexual 

 function of a woman lasts forty years and 

 assuming, further, that every ten months 

 of these years would be taken up by a preg- 

 nancy, then only fifty ova would be re- 

 quired of the ovary. But assuming even 

 that a regular menstruation is an essential 

 and indispensable part of the sexual func- 

 tion, then five hundred ova would be the 

 maximum that the function of reproduc- 

 tion could Tise. Nevertheless, we find that 

 the ovary of the new-born female child 

 possesses between 100,000 and 400,000 eggs, 

 and at the time of puberty there are still 

 about 30,000 ova ready to enter upon their 

 possible mission. That is, the ovary con- 

 tains at puberty sixty times more ova than 

 the body could possibly ever employ. But 

 there is an incomparably greater waste in 

 the provision of the male germ. Accord- 

 ing to Rohde each ejaculation contains 226 

 millions of spermatozoa. Now we know 

 that of all these legions only one single 

 spermatozoon is required and only one can 

 be used. What a marvelous waste of liv- 

 ing cells for the sake of assuring the per- 

 petuation of the species. But there are 

 some attenuating circumstances. With a 

 velocity of only 0.06 of a millimeter per 

 second, with the dangers of crossing the sea 

 of fatal acid vaginal secretions and with a 

 resistance to the onward progress offered 

 by the cilia of uterine epithelium swaying 

 in the opposite direction, not too many of 

 the storming millions stay in the race and 



have a chance to reach the goal. At any 

 rate, it is not by economy, but by immense 

 waste of cell life that the chance for con- 

 tinuation of the species is assured. 



In strLking contrast to the extreme lux- 

 uriousness of provision of tissue in the 

 organs previously described stands out the 

 comparative scantiness of cell tissue in 

 some organs — if we may call them so— of 

 the central nervous system. The centers 

 of the medulla oblongata, for instance, pre- 

 sent such minute bodies that hardly a part 

 of any center could be injured without en- 

 dangering the entire function. Any injury 

 to the respiratory center suspends imme- 

 diately and permanently the function of 

 respiration. The possible existence of some 

 respiratory centers in the spinal cord does 

 not alter the practical result. The same 

 applies to the center of deglutition. The 

 blood pressure, as we shall see later, is pro- 

 vided with quite a large number of safety 

 factors. However, the immediate effect of 

 an injury to the vasomotor center is a 

 dangerous drop in blood pressure, the resti- 

 tutions and compensations over which the 

 organism commands are not forthcoming 

 until after a long interval. We may point 

 out, however, that the central nervous sys- 

 tem is provided externally with factors of 

 safety against two of its main enemies: it 

 is protected by a bony encasement against 

 any physical injury and especially is the 

 medulla oblongata well hidden away, and 

 it is protected by an abundance of blood 

 vessels against dangers of ansemia. 



Following the old divisions of the organs 

 of animal life in reproductive, vegetative 

 and animal systems, we may say, perhaps, 

 that the reproductive system is provided 

 most and the animal system is provided 

 least with factors of safety, while in the 

 vegetative system, which in that regard 

 occupies a middle position, those organs 

 which seem to be less well differentiated, 



