BARR ON ASEXUAL DIMORPHISM. 15 



aclaiit«'d 1o its use. Must we not, thoii, believe that the so called 

 "sexual attraetiou" between s|)t'rni and egp,- is the seekinji; by the former 

 of that which enables it to continue its (existence — that it is a phenouie- 

 Tuui of the search for subsistence — an attraction chcniical. jih.vsical or 

 mechanical lo\\ar<l that which it must have to supply material upon 

 which its katabolic tendencies may work? 



The snuillei- cell, then, seeks the larger, enters it, feeds upon it, grows 

 and ](ossess('s itself of the (h'velojnncutal machinei-y thei-ein (energizes 

 it. if you please) and proceeds to build up a "body." What is it then, 

 that develops — ^tlie ovum or the sperm? 



The value of sexual as compared to asexual reproduction does not 

 admit of debate. On many counts ci-oss-fei-tilization, which were im- 

 jiossible -without union of the germ-nuclei, is a benetit. Evidence on 

 this i)oint is overwhelming. Propagation without amjdiimixis, at 

 least undei' a variable environment, is not a success. Sexualitv, bv com- 

 ]>iniug the geiin-]ilasnis from individuals of different ex]»eriences, Avidens 

 variation, and the power of variation, and adapts to a wider environment. 



Fundamentally the sperm is not alone the energizing, it is the actual 

 being that continues the race. The ovum is primarily but the bricks 

 and mortar, as it were, that the sperm, the builder, employs in the 

 construction of the house. 



Coming, however, into such relation to this cell as to employ its 

 machinery it necessarily is brought to the center and thus to the nucleus 

 of the egg. Entangling this in its meshes, the female i)ro-nucleus is 

 perforce incor])orated in the ])lan. Rut the mechanism is not adapted to 

 the utilization of so many chromosomes. There are twice as many as 

 can be utilized by the ovular machinery. The remainder are therefore 

 set aside, and, as only impedimenta in subsequent processes, are cast 

 out as a second polar cor])Uscle. That this reducing division in both 

 egg and sperm later occurs, by tachygenesis, before fertilization is but 

 an added safeguard to assure perfect cross-fertilization; for only thus 

 can there be certainty of equal representation or, indeed, of one parent 

 being at all represented in fertilization. 



I'arthenogenesis need not be considered a serious infringement of 

 the usual law. To be sure it does not secure amjjhimixis but the data 

 l)oint to an auto-fertilization and whether the second polar body is 

 extruded and then reenters the egg or is retained throughout is a matter 

 of mere developmental detail. That the egg may develop without ex- 

 terior fertilization need surprise none though Loeb's* experimental 

 proof is indeed a brilliant i)iece of work. That it will do so if only 

 proper stimulus be afforded is a necessarj' consequence of the theory 

 here presented. 



Summary: — 



We are led, then, to believe: 



First, Keproduction (cell-division) arose from unfavorable nutritive 

 conditions, i. e., at the limit of growth. 



Second, In the struggle for existence large and small cells arose 

 (asexual dimorphism) to meet its exigencies in two ways. 



Third, The ovum and the first polar body are simply the result of an 

 unequal division. 



* Amer. Jour. Physiol., Oct., :1899. 



