SCIENCE-GOSSIP. 



283 



the stage which succeeds the egg and precedes the 

 pupa. ("Century Dictionary," article " Larva.") It 

 is, according to many writers, including the late 

 Prof. Westwood (" Text Book," p. 168), analogous to 

 the period of infancy (i.e. to " the young ") of the 

 higher animals ; and certainly the young of many 

 animals, especially the males of birds, differ far 

 more from their adolescent stage than do the 

 larvae of many insects from their pupas. For 

 example, the chicken bears much less resem- 

 blance to the cockerel, than the larval cricket 

 or cockroach to the pupa of the same. Then, 

 according to the best authorities, the sex of 

 the caterpillar, having been decided in early 

 embryo, before the foetal stage, and of course a 

 comparatively considerable time before exclusion 

 from the ovum, cannot possibly be altered by 

 feeding or by any other agency. The larval period, 

 too, is pre-eminently the age in which the greatest 

 amount of assimilation and growth takes place, and 

 large quantities of food have to be absorbed for 

 the purpose of providing the necesasry material ; 

 not only this, but in such species as undergo a 

 pupal metamorphosis considerable reserves have to 

 be stored up in readiness for elaboration in the 

 quiescent stage, for then cell formation is very busy 

 perfecting the reproductive apparatus and com- 

 pleting the secondary sexual characters, including 

 the organs of sound, etc., preparatory to the 

 attainment of the adult state. These organs, 

 for producing sound, whether vocal or mechanical, 

 freshly acquired or altered, as the case may be, seem 

 to be very characteristic of the male adolescent or 

 pupal condition. The boy's voice begins to "crack " 

 or " break " and ultimately deepens ; the puppy's bark 

 becomes "doggy"; the cockerel tries to crow; 

 the thrush commences to sing ; the death's-head 

 moth "squeaks" while yet in the chrysalis; the 

 grasshopper chirrups in a mild way ; and it may 

 be added that the frog makes an effort to croak ; 

 and these phonetic signs of approaching maturity 

 are accompanied by the appearance of other 

 secondary sexual characters, varying according to 

 the species to which they pertain, of which I may 

 specially mention the vocal sacs of Rana escuknta. 



To sum up : the batrachian larva is, when 

 first excluded, a sexless, limbless egg, provided 

 with a yolk upon which its development depends ; 

 its digestive organs are very rudimentary indeed, 

 and the duration of its larvahood stops short of the 

 foetal stage. The newly-excluded larva, from 

 the standpoint of the entomologist, on the other 

 hand, has a decided and unalterable sex ; it 

 possesses six or more permanent legs, according 

 to the order to which it belongs, and, of course, 

 contains no yolk ; its digestive organs are more 

 vigorous than in any other stage, and the duration 

 of its larvahood commences from its exclusion from 

 the egg, that is after the foetal stage, and extends 



M : 



to the pupal, or adolescent state. In other words, 

 the one terminates before the foetal stage, the 

 other commences after it. 



In conclusion, my object in penning these notes 

 is not to advocate any change of nomenclature for 

 these respective phases of life, but, as originally 

 stated, to warn the student against drawing any 

 comparisons between the larvae of frogs and 

 those of insects. A tadpole is an anomalous 

 creature, quite the exception to the rule of nature. 

 It is not that, in itself, it is so extraordinary, for 

 all vertebrata and invertebrata, from man down- 

 wards, pass through a corresponding stage. The 

 marvellous thing about it is that an early embryo 

 should be excluded from its envelope, and yet be 

 viable, independent, free and locomotive, while, in 

 all other animals, this stage of life takes place 

 within the privacy of the membranes in utero, the 

 eggshell, or other protective covering. There is 

 not in the animated world, so far as I know, a case 

 which presents a parallel. The nearest approach 

 to it must be sought amongst the Marsupalia. 



Folkestone ; January, 1896. 



Tunbridge Wells Congress. — We under- 

 stand that definite arrangements are being made 

 for a Congress of societies devoted to natural 

 science in the South-east of England, which will 

 be held at Tunbridge Wells, on Saturday, April 25th 

 next, under the Presidency of the Rev. T. R. R. 

 Stebbing, M.A., F.L.S., who is this year the 

 president of the local society, to discuss this and 

 other subjects. The visitors are invited by that 

 society to attend on the Saturday morning for a 

 ramble to inspect the geological features of the 

 town, and also to lunch with the members. Among 

 others, the following are the subjects for discussion 

 at the Congress, which meets at 3.30 o'clock : 

 " Travelling Lantern-Slide Scheme," introduced by 

 H. E. Turner, B.A., B.Sc, Hastings Natural 

 History Society ; " The British Association Photo- 

 graphic Committee's Work," W. W. Watts, M.A., 

 Geological Survey, Jermyn Street, S.W. ; " Re- 

 delivery of Lectures before other Societies," E. A. 

 Pankhurst, Hon. Sec. Brighton Natural History 

 Society ; " Winter Programmes," G. Abbott, 

 M.R.C.S., Tunbridge Wells Natural History 

 Society ; " Summer Excursions and Field Work," 

 Professor G. S. Boulger, F.L.S., F.G.S., Geolo- 

 gists' Association ; " The Protection of Footpaths, 

 Commons, etc.," L. W. Chubb, Commons Preser- 

 vation Society, Westminster ; " Congress, 1S97, — 

 Date, Time, and Place of Meeting, Rules," Capt. 

 Gordon McDakin, Dover Natural History Society ; 

 interchange of microscopical slides, books and 

 magazines with affiliated societies and similar 

 associations in other districts. Further informa- 

 tion may be obtained from Dr. George Abbott, the 

 Hon. Secretary, 57, The Pantiles, Tunbridge Wells. 



