504 



NATURE 



[August 23, 191 7 



be widely and assiduously disseminated. In the 

 main Dr. Hill's book is a useful contribution 

 towards this object. 



In chap, i., on "The Need of Food," the author 

 has put the case clearly, though some improve- 

 ments mig-ht be suggested. The calorimeter 

 illustrated, for instance, is far removed from that 

 actually used. Nor is it strictly accurate to say 

 that the body must receive as much nitrogen as 

 the kidneys excrete in urea. What really happens 

 is that the kidneys excrete as much urea as is 

 presented to them to be eliminated, this amount 

 being no trustworthy measure of the nitrogen 

 needs of the body. 



In chap. ii. an attempt is made to give a simple 

 account of the chemistry of food. It is doubtful 

 if it is worth its place. 



The main part of the booklet is devoted to a 

 consideration of the nourishing value of various 

 foods. The information is on the whole sound, 

 though in many ways this chapter could be 

 shortened with advantage. Some statements also 

 require qualification, such as that the presence of 

 sugar with protein in the stomach leads to a forma- 

 tion of uric acid in the system; that "gelatin can- 

 not take the place of protein" (p. 35) ; that 

 "gastric juice does nothing to break up the fat- 

 saturated lumps " of flour and butter in pastry 

 (pp. 36 and 37) ; and that no other kind 

 of food gives so lo-ood a return for its cost as 

 cheese. 



Too much stress also is laid on the content of 

 protein in a food as a measure of its nutritive 

 value, and the author argues too rigidly from the 

 assumption that a working man requires 4 oz. 

 {ii3'5 grm.) of protein per day in his diet. 



On p. 13, by oversight, a man's weight — 

 75 kilos — is translated as 13 st. 9 lb., whereas it 

 should be II St. II lb. 



The booklet should prove useful. 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for 

 opinions expressed hy his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



The Terminology of Parthenogenesis. 



The word "parthenogenesis" has become established 

 in biological science to signify the production 

 of offspring by a virgin mother. The term 

 does not embrace reproduction by buds or by fission, 

 but refers to parentage by a mother who produces egg- 

 cells similar to those which are, in the vast majority of 

 instances, fertilised by male sperm-cells before pro- 

 ceeding to develop. In these instances (distinguished 

 as instances of "parthenogenesis") the egg-cells pro- 

 ceed to develop without fusion with the male repro- 

 ductive element or sperm-cell. 



Parthenogenesis may accordingly be defined as an 

 exceptional and historical!}' super-induced modification 

 of the normal process of sexual reproduction or gamo- 



NO. 2495, VOL. 99] 



genesis in which the female gamete or egg-cell does 

 not unite with a male gamete or sperm-cell to form 

 a "zygote," but proceeds to develop independently. 



The term should not be applied to reproduction by 

 unfertilised unicellular "spores" common in the lower 

 plants and protozoa, nor to any cases except those in 

 which the " parthenogenetic" reproductive cell is either 

 (i) a normal egg-cell capable of sexual zygosis, or (2) 

 demonstrably a comparatively recent modification of 

 such an egg-cell. The latter is an important special 

 group, and at one time these modified egg-cells — in- 

 capable of fertilisation — were incorrectly described as 

 " pseud-ova " (Huxley). The egg-cell thus independ- 

 ently developing may be described as " autoblastic " 

 and the process as " autoblastesis." And again the 

 autoblastic egg-cell may be described as " lipospermic " 

 and the embryonic history as one characterised by 

 " lipospermy " or " lipospermia." 



A difficulty of nomenclature has lately arisen inj 

 describing and discussing the offspring so produced — ' 

 for instance, when the eggs of the frog have been ex- 

 perimentally induced by the mechanical method of 

 Bataillon (scratching with a needle) to develop so as to 

 give rise to tadpoles, and even adult frogs, without 

 fertilisation by sperm-cells. By oversight the tadpoles 

 so produced have been referred to as '"parthenogenetic," 

 and by a similar error the broods of greenfly produced 

 without the intervention of a male parent have been 

 called "parthenogenetic young." Clearly the word 

 "parthenogenetic" has been, and must be, used to 

 describe the virgin mother, and therefore cannot at 

 the same time be applied to her offspring without 

 causing confusion. It seems to me that the word 

 " impaternate," or " fatherless," should be used for the 

 offspring. I have failed to excogitate any other term 

 which will so well meet the case. 



If we call individuals so produced "autoblastic" — a 

 term applicable to the egg-cells which give rise to 

 them— we leave it doubtful as to whether we may not 

 be referring to their future reproductive capacity rather 

 than to their origin; and if we call them "'lipospermic" 

 we may possibly intend by this word to indicate that 

 they are devoid of male reproductive gonads, and not 

 merely that no sperm-cells were concerned in their 

 genesis. The term "impaternate" is readily intelli- 

 gible and admits of no such ambiguity. 



A further difficulty in regard to the nomenclature of 

 virgin reproduction or f arthjgnogenesis is that the word 

 "virgin" and its Greek equivalent refer to the condi- 

 tion of the mother, and not to the history of the egg- 

 cells which she produces and passes from her body. 

 The "virgo intacta " is an adult female who has not 

 been "covered" or "impregnated" by a male, or, to 

 use another term, has not been "mated." In most 

 species of frogs and fishes, and in many other aquatic 

 animals, the female parent is always a ''virgo intacta." 

 Such females are always "parthenogenetic" in the 

 strict sense of the word. The fact that the eggs are 

 not "autoblastic," but are fertilised after they leave 

 the mother's body, does not alter her physiological con- 

 dition or "status " in any wav as compared with that 

 of a mother whose eggs on being deposited by her are 

 capable of "lipospermic" embryogenesis. She is never 

 "mated" or "impregnated." The difference between 

 her and the more familiar impregnated or fecundated 

 mother arises from the persistence in the one case 

 of the original and primitive method of free dis- 

 charge of both the female and the male reproductive 

 cells into the water in which the parents live, and, by 

 contrast, the secondary development in the other case 

 (comprising a vast variety and number) of arrange- 

 ments for the fertilisation of the egg-cells while still 

 actually within the protective body of the mother or 

 in close contact with it. These ' secondarv develop- 



