August 2^, 191 7] 



NATURE 



505 



merits are determined by the fact that they favour 

 both economy and certainty in the operation of the 

 male gametes or spermatozoa, and by their provision 

 of advantageous maternal protection to the minute 

 egg-cells and the early stages of their gro\\-th when 

 fertilised. In non-aqiiatic animals intra-matemal fer- 

 tilisation of the egg-cells is obligatory. 



The . egg-cells which are freely discharged and fer- 

 tilised by ffee-swimming sperm-cells " in the open " 

 may be called '' planktogamic" (plankton = freely 

 swimming), whilst egg-cells which are subjected to the 

 secondary protective arrangements may be called either 

 "hysterogamic'' (hysteron = uterus), if fertilised within 

 the oviductal chamber of the mother, or ""propylo- 

 gamic" (propylon = a gateway), if fertilised on the sur- 

 face of the mother's body or in immediate relation 

 thereto fas in the case of many Crustacea and of some 

 .Amphibia). 



There is no word in use to indicate the physio- 

 logical status of an adult female which is no longer 

 a "virgin," but has been 'mated" or "covered," and 

 has received into her oviduct sperm-cells from a male. 

 We might designate such a female as a " mate " in con- 

 trast to a "'virgin," but "mate" is in ordinary use 

 for any kind of comrade. Though the words "wife" 

 and "spouse" have too definite a reference to human 

 legal and social status, yet the Latin word " conjux," 

 implying as it does a " conjugium " (the significance of 

 which is given in Virgil's account of wind-fertilised 

 mares, "'sine ullis conjugiis vento gravidae"), might 

 well be used as the antithesis of "virgo." Any female 

 bearing hysterogamic egg-cells is accordingly a "'con- 

 jux," whilst one discharging "planktogamic," or it may 

 be ■ propylogamic," egg-cells is a "virgin." 



The existence of " hysterogamesis " leads on to that 

 phenomenon which was by Aristotle regarded as a 

 highly important "differentia*' in the classification of 

 animals, and is loosely described as "viviparity." 

 .\nimals which pass a large part of their embr}onic 

 growth within the mother's body and are born naked 

 and with much of the shape and locomotive capacity 

 of the adult are called "viviparous." But really all 

 animals are viviparous, for the birth-product is a 

 living thing whether it is a naked egg-cell or more 

 or less advanced in development. The enclosure of the 

 birth-product in a shell or case, which has given rise 

 to the term •"oviparous," is not of any value as indi- 

 cating the real degree of development of the young at 

 birth, for in some case? unfertilised egg-cells, in others 

 mere discs of developing embryonic cells (as in birds, 

 etc.), and in yet other cases well-shaped young rang- 

 ing from the early larva of some invertebrates up to 

 the completely formed miniature of the adult, as in 

 some of the shell-bearing snails, may be enclosed 

 within an eggshell when " laid " by the mother. There 

 is accordingly no great general importance to be 

 attached to the distinction between "viviparous" and 



'oviparous'" animals. The eggshell has, of course, its 

 orotective value, but the exact phase and nature of the 



iving thing within it must be considered in any com- 



- m of the reproductive processes of different 



als. 



J 1 may now show how far the considerations and the 



ilescriptive terms here suggested apply to certain 



tl cases of what is usually called parthenogenesis, 



is better designated "'autoblastesis " or " lipo- 



t'^rmia." 



1 (i) The greenflies, or Aphides, are, as are all insects, 



jharacteristically hysterogamic. They are propagated 



|y males and mating females (conjuges) in autumn. 



l>ut the spring and summer broods are females only. 



jhey are virgins, and produce true egg-cells which are 

 utoblastic and develop into several succeeding genera- 

 of impaternate females (lipospermia or partheno- 

 XO. 2495, VOL. 99] 



genesis). The egg-cells of these virgin mothers are 

 modified so as to be incapable of zygosis, whilst the 

 maternal structures connected with hysterogamesis 

 (maternal fecundation) are aborted, although the intra- 

 uterine gestation is retained and the young are bom 

 naked in a fully formed condition, whence they are 

 said to be "viviparous." 



(2) The phyllopod Crustacean Apus normally gives 

 birth to egg-cells encased each in a delicate eggshell. 

 These are autoblastic, and produce with ven>' rare 

 exceptions only impaternate females. At rare inter\-als, 

 owing to conditions not ascertained, a few impaternate 

 males are hatched from some of the eggs, and "pro- 

 pylogamic " fertilisation of the eggs of some of the 

 virgin mothers of the same generation then takes place. 



(3) The breeding queen bee (Apis) and the breeding 

 queens of some other hymenopterous insects are at the 

 same time both parthenogenetic and gamogenetic I They 

 are definitely " conjuges," or mated females, but some 

 of their eggs are hysterogamic and give rise to females 

 only, whilst others are agamic (lipospermic) and give 

 rise by autoblastesis to impaternate males (drones) only. 

 This remarkable double character of the "queen" is 

 due to the fact that the sperm-cells of the drone 

 received by her into her spermatheca can be withheld 

 from contact with the egg-cells about to be laid or 

 admitted to them according to circumstances. Fer- 

 tilisation of the egg-cell is (to use a French term) 

 " facultative." 



(4) Silkworm moths and some other female Lepi- 

 doptera sometimes lay eggs without having mated or 

 come into contact with a male. Not infrequentlv ihese 

 eggs, which in normal conditions should be hystero- 

 gamic, proceed to develop by autoblastesis, and produce 

 impaternate males and females. This lipospermic re- 

 production is stated to have been experimentally car- 

 ried out through three successive generations. The 

 autoblastesis can be favoured, if not determined, by 

 brushing the shell of the egg with a camel 's-hair 

 pencil. 



(5) The female of the common frog is, like that of 

 nearly all bony fishes, in all circumstances a 

 "virgin." Her eggs are planktogamic. Other 

 Amphibia may be propylogamic or even hysterogamic. 

 When received into carefully purified water, the un- 

 fertilised eggs of the common frog, which are naturally 

 envelopecl, each in a jelly-like coat, can be caused to 

 enter upon the curriculum of cell-division and em- 

 bryonic growth by scratching the surface of the dark- 

 brown egg-cell . with a needle. The impaternate off- 

 spring thus produced have been reared to late stages 

 of the tadpole phase, and more rarely to the adult 

 form. The impaternate or fatherless young thus reared 

 have, so far as at present recorded, always proved on 

 examination to be males. 



Other cases of lipospermia or autoblastesis, sucfT as 

 those revealed by the experiments of Loeb, Deslages, 

 and others, could, I think, be with advantage sum- 

 marised by the use of some such nomenclature as that 

 here suggested. .Autoblastesis is contrasted with 

 gamoblastesis, but its occurrence is not " spontaneous." 

 It depends upon either mechanical or various chemical 

 conditions which could be enumerated and classified. 



E. Ray Lankester. 



The Scandinavian Languages. 



In* the scheme of examination (see Nature, vol. 

 xcix., p. 475), it is curious to see Norwegian and 

 Danish, which have the same dictionan,-, separated 

 bv the verN' different Swedish language. 



T. R. R. S. 



August 14. 



