54 



SCIENCE 



[N. S. Vol. XXIX. No. 732 



characteristic mode of development of the 

 organism (which is only another way of 

 saying its heredity) is as definitely con- 

 ditioned by its environment as by those 

 internal agencies that we ascribe to the 

 specific organization of the germ. The end 

 result is a product of internal and ex- 

 ternal factors acting together. But the 

 distinction I have drawn is nevertheless 

 perfectly real and definite, as will perhaps 

 appear more clearly if the inquiry is stated 

 in the following way : 



1. Is the germ originally of indetermin- 

 ate sex, or sexless, being determined as 

 male or female at some later period by 

 corresponding differences of conditions ex- 

 ternal to the germ? Or, 



2. Given an identity of external condi- 

 tions in each case, is the germ prede- 

 termined from the beginning as male, 

 female or hermaphrodite by internal 

 factors of its organization? And 



3. If such predetermination exists, what 

 is its physical basis? 



These questions can not be adequately 

 considered without some preliminary ex- 

 amination of the sexual distinction in gen- 

 eral. We use the words "male" and 

 "female" in a double sense. In the orig- 

 inal and still common one they denote 

 certain characteristics of the individual 

 body, primarily those shown in the repro- 

 ductive organs, secondarily those of other 

 organs. Later the same terms were often 

 applied to the germ-cells themselves, the 

 eggs being spoken of as the ' ' female germ- 

 cells," the spermatozoa as the "male"; 

 and this usage is often met with at the 

 present time, even in technical treatises. 

 But confusion thus at once arises; for, as 

 we shall see, there are many cases in which 

 the eggs or the spermatozoa are themselves 

 of two classes which are respectively male- 

 producing and female-producing, and have 

 accordingly been spoken of as "male" and 

 "female." It is therefore preferable, at 



least in case of the higher organisms, to 

 designate the gametes as paternal and ma- 

 ternal, restricting the words male and 

 female to the body by which they are pro- 

 duced. In the case of unicellular forms, 

 where every cell may be potentially or 

 actually a gamete, it is doubtful whether 

 the words male and female should be used 

 at all. In the isogamous forms, some of 

 which occur among the lower multicellular 

 types, the gametes are of equal size and 

 similar structure, so that every visible 

 sexual distinction may vanish. But even 

 here the gametes are in some cases known 

 to be of two physiological classes (as in 

 certain simple algae and fungi) each of 

 which unites only with the other. A 

 primitive form of sexuality is therefore 

 present, but the gametes and the indi- 

 viduals that produce them can only be 

 designated by non-committal terms such as 

 "plus" and "minus" (Blakeslee). 



Even in the higher plants and animals 

 caution is necessary in our use of terms. 

 Primarily we designate as males and 

 females individuals that produce respect- 

 ively spermatozoa and eggs, or their an- 

 alogues; and as hermaphrodites those that 

 produce both kinds of gametes. In the 

 flowering plants confusion arises from the 

 transference of these terms by analogy to 

 the non-sexual generation or sporophyte; 

 and a species may be hermaphrodite or 

 monecious in respect to this generation 

 and diecious in respect to the sexual 

 generation or gametophyte. But whether 

 in this sense or in the original one the 

 sex-distinctions are not fixed or absolute. 

 Not infrequently in hermaphrodites the 

 production of eggs and of spermatozoa 

 takes place at different times, so that the 

 organism passes through a functional male 

 stage and a functional female one. Con- 

 versely, it is a familiar fact that the sexual 

 characters of diecious forms are seldom 

 completely separate. Each sex frequently 



