NOTES AND CONCLUSIONS. 



375 



doubtless because chiefly of the small number and the 

 kinds of hybrids studied. In summing up the characters 

 that are the same as or inclined to the seed parent and the 

 pollen parent, respectively, it was found in the 1,018 

 starch reactions that the seed parent is, on the whole, 

 distinctly more potent than the pollen parent, while in 

 959 tissue characters the parental influences are equal. 



SPECIES PARENTS VEKSUS SEX PARENTS. 



The parental properties referred to in the preceding 

 section are, in an important sense, illusory, because they 

 indicate sexual instead of species characters. The terms 

 seed parent and pollen parent have been used in this re- 

 search, in the conventional sense of the botanist and horti- 

 culturist, that is, without necessarily implying or even 

 inferring unisexuality of the plants. This usage, to- 

 gether with the employment of the signs 9 and $ , may 

 carry the impression that the parents of the hybrids 

 are correspondingly female and male, but all of the 

 parents are flowering plants in which in each individual 

 there are produced both female and male gametes. Each 

 plant is, therefore, female or male in reproduction in 

 accordance with whether it furnishes the seed or the 

 pollen, irrespective of the actual sex of the organism. 

 A concrete illustration of this paradoxical statement is 

 found, for instance, in Cypripedium spencerianum and 

 C. villosum, which have been reciprocally crossed, yield- 

 ing the hybrids C. latliainianum and C. lathiamianum 

 inversum, these hybrids not being identical but very 

 closely resembling each other (page 338 et seq.). In the 

 first cross the seed of C. spencerianum was fertilized by 

 the pollen of C. villosum, and in the second cross the 

 pollen of C. spencerianum fertilized the seed of C. vil- 

 losum, thus reversing the parentage. Inasmuch as each 

 plant is precisely the same in both crosses, it is evident 

 that the properties ascribed to C. spenrrrianum as the 

 seed parent and the pollen parent, respectively, are identi- 

 cal and therefore that they are, as far as we can discern, 

 peculiarities of species and not of sex. However, the 

 differences in the offspring of reciprocal crosses show that 

 while the seed and the pollen carry species-characters 

 they also transmit certain obscure properties that are 

 peculiar to each of the sex elements. 



All living tissues have without question species-h/pes 

 of metabolism, and, as a corollary, species-types of com- 

 plex organic metabolites (see preceding memoir, Car- 

 negie Institution of Washington, Pub. No. 173, page 12) ; 

 and if the tissues are further characterized by femaleness 

 or maleness, they must have the corresponding sex-fi/pcs. 

 In bisexual or monoecious 1 organisms, such as the plants 

 used in this research for the sources of the starches and 

 tissues, the structures, processes, and products, with the 

 exception of those belonging to the primary sex organs, 

 are without determinate sex characters, yet for well- 

 known reasons it is certain that they possess inherently 

 potentialities of both sexes. In unisexual organisms, as in 

 certain plants and in all normal mammalia, there must 

 be both species-types and sex-types. Therefore, in the 

 first group of the properties are broadly speaking or pre- 

 eminently those of species, and in the second those of 

 species and sex. 



That there are species-types is convincingly shown 

 by the distinguishing features of species ; and that there 

 are very definite sex-types has been rendered positive, 



especially by recent investigations. For instance, in 

 gynandromorphs (as noted in a bullfinch by Poll, in a 

 chaffinch by Weber, in a pheasant by Bond, and in men, 

 dogs, guinea-pigs, crabs, bees, ants, butterflies, and moths 

 by various writers) the structures of the two sides or of 

 the anterior and posterior parts of the body, or of differ- 

 ent organs or of parts of an organ are oppositely 

 sexed. Geoffrey Smith found that the bloods of female 

 and male spider crabs differ, and Stecke in investigations 

 with moths noted that not only do the bloods of the sexes 

 differ but also are as much unlike as are those of indi- 

 viduals of the same sex of different species. The bloods 

 of woman and man, and of the sexes of certain other 

 mammals, are not identical. The ovaries and testicles 

 are specifically female and male organs, and the egg, 

 spermatozoon, and sex hormones are similarly sexed. 

 Moreover, during the existence of the germplasm, and 

 even in some organisms long after development has 

 proceeded, there is a period of sexual plasticity during 

 which various factors may be directly operative, on the 

 egg or indirectly through the parent, or directly on the 

 metabolic processes of the individual, to lead to the 

 development of either sex or of either female or male 

 secondary characters, as the case may be, and hence to 

 corresponding female or male types of metabolism and 

 metabolites. In studies of the pupa of butterflies, Stand- 

 fuss found that by the influence of temperature the 

 female can be made to assume the male type. Geoffrey 

 Smith noted that the sacculinated male spider crab (that 

 is partially or -completely parasitically castrated) be- 

 comes markedly feminized, even to the extent of rudi- 

 mentary eggs being formed in the testes. Riddle records 

 in studies of pigeon eggs a transmutability so marked 

 that eggs having one sex tendency may be caused to be- 

 come oppositely sexed. Steinach and others in ovarian 

 and testicular transplantation experiments have shown 

 that the female can be masculinized and the male femi- 

 nized. Moreover, the potent influences of food, of an 

 excess or deficit of water in the egg, of the energy of 

 oxidative metabolism, and of light on sex control are 

 well known. And in the human being indications of 

 female and male types of metabolism and metabolites 

 are to be found among differences in the sexes in bodily 

 structures, in the composition of the blood and certain 

 other parts, in the actions of a number of medicinal sub- 

 stances and certain internal secretions, in the properties 

 of the sex hormones and of some other substances that 

 are produced by sex organs other than the ovaries and 

 testes, in basal metabolism, in psychic phenomena, etc. 



The factor or factors that determine species-types are 

 not known, nor have we much definite knowledge of those 

 which control sex -types, but it may justly be assumed that 

 what is learned of one is applicable in principle to the 

 other. Since the discovery of the sex hormones there has 

 boon a tendency generally to attribute to them the deter- 

 mination of secondary sex characters, but there are 

 reasons for believing that other substances, as yet un- 

 known, may be similarly potent. Thus, Meisenheimer 

 showed by the results of experiments with the larvae of 

 the gypsy moth that secondary sex characters are devel- 

 oped without material modification after the removal of 

 the ovaries and testes ; and it is evident that in gynandro- 

 morphs both sex hormones circulate throughout the 

 organism, and thus reach every tissue, yet some parts 



