March 22, 1877] 



NATURE 



451 



each was capable of rotating (though with very great friction). 

 When brought near each other they repelled each other forcibly, 

 I experimented with these pieces for several minutes without per- 

 ceiving any diminution in their electr.fication. Both sides of the 

 paper seemed to be in the same condition. I then laid them 

 down, and left the room to fetch a piece of sealing-wax to test the 

 nature of the electricity. But by the time I returned, all trace 

 of electricity was gone, and by no means could I repeat the ex- 

 periment so as to get the slightest charge of electricity. 



It is more than probable that the eKctricity was developed by 

 the chemical action of combustion of the coals, and that the hot 

 air rising up and brushing past the paper acted as a carrier of 

 electricity of one kind to the paper, and of the opposite kind 

 from it, until it acquired a very high potential. I3ut it would 

 be interesting to learn exactly in uhat manner this action takes 

 place, and whether the electrification was positive or negative. 



Andersonian College, Glasgow George Forbes 



Strange Star. — Meteor 



On going out last Saturday evening about 8.55 P-W. my atten- 

 tion was arrested by a large deep red star in Serpens which I had 

 never seen before. Its magnitude was greater than Arcturus, 

 though its deep colour made it feem less bright. About ten 

 minutes afteiwards I saw it increase ;n d diminish in magnitude 

 two or three times producing the effect similar to a "flashing " 

 light on the coast, after which it suddenly disappeared. 



On the same evening, at 9.56, I saw a very fine meteor of a 

 bright pale blue colour with coruscations of ruby colour at the 

 nucleus. Its course was from Gemini over Aldebaran, disap- 

 pearing below Pleiades. Of a long pine-cone shape, duration 

 about three seconds. W. M. 



Gunnersbury, March 19 



SCIENCE IN GERMANY^ 



THIS book forms a continuation of the researches which in 

 vol. i. treated of the season dimorphism as the result partly 

 of exterior influences and partly of atavism. The present 

 (second) volume comprises : (i) the origin of the markings 

 upon caterpillars ; (2) on the phyletic parallelism in meta- 

 morphous species ; (3) on the transformation of the Mexican 

 Axolotl into an Amblystomaj (4) on the mechanical con- 

 ception of nature. The third treatise was pubhshed separately 

 some time ago and was reviewed in Nature ; here we par- 

 ticularly wish to draw the attention of the lovers of natural 

 science to the first paper. Weismann tries in the treatise in 

 question to prove by his observations, and the deductions there- 

 from, that exterior influences and natural development or adap- 

 tation (Naturzuechtung) only can be the causes of the markings 

 upon caterpillars. The observations referred to were made 

 upon the caterpillars of several genera of Sphingidie^ and relate 

 to the history of their development. 



I. CJutrocampa. — The caterpillars of Ch. elpenor, which have 

 just left the ova, show no markings of any kind in this first stage, 

 being of a uniform greenish colour ; after the first change o( skin 

 (second stage) they show a bright longitudinal streak on each 

 side, between the dorsal line and the line of breathing apertures 

 (stigmata). To this first streak Weismann gives the name of 

 "subdorsal streak," In the third stage eye-shaped spots form 

 in the fourth and fifth segments, inside of these streaks, and 

 these are completely developed in the following stages, i.e., after 

 the subsequent changes of skin, while at the same time the sub- 

 dorsal streak decreases and leaves only imperfect traces. In the 

 fifth stage the greenish colour changes to a brownish one, and 

 the horn at the tail of the caterpillar becomes shorter. In the 

 sixth and last stage the other segments begin to show eye-spots, 

 but these are not developed to perfection. Ch. porcellus shows 

 the same form and development of the larva, with the only dif- 

 ference that most of the phenomena occur one stage earlier than 

 with Ch. elpenor. This conformity and accord of both genera 

 in the order in which the markings upon the caterpillars appear 

 and are developed, lead to the conclusion that the markings were 

 acquired in the same order during the progress of development 

 (phylogeny) of these caterpillars ; the oldest form (a) therefore 

 showed no markings at all even when perfectly developed ; 

 the following form [b) had only the subdorsal streaks ; then in 

 form {c) the eye-spots occurred in the fouith and fifth segments, 

 and finally in all segments (form d). It is probable further, 

 that of the two genera of caterpillars now living, Ch. elpenor 



'Weismann, " Studien nir Descendenztheorie "(" Researches on the 

 Oescent Theory"). Vol. ii. On the last Causts of Transmutations. 



is the original, i.e., older form, on account of its still showing 

 the different stages of development in their completeness ; the 

 younger or more advanced form, viz., Ch. porcellus, proves 

 that each new marking, acquired during the progress of deve- 

 lopment, appears first in the later stat;es and then gradually 

 extends to the earlier stages. The whole of this view is well 

 supported by the markings upon the complete form of the 

 other species belonging to the genus Chmrocatnpa, of which the 

 development of the larva is still unknown in its different stages. 

 These other species may be divided into three groups, corre- 

 sponding to forms b, c, and d of the phylogeny in such a manner 

 that wherever the subdorsal streak remains in perfection, the 

 eye-spots are not developed, and wherever these show them- 

 selves the subdorsal streak is decreasing. Form a (first group) 

 is known in the full-grown caterpillars of three species (^Ch. 

 syriaca, Daraspa myron, and D. chcerilus) ; to the second group 

 (form c) belong the above described Ch. elpenor and Ch. porcellus, 

 together with several others ; the last group (form d), which 

 shows completely developed eye- spots on all segments, is even 

 more numerously represented by Ch. bisecta, oldenlandice, alecto, 

 actceus, tersa, and celerio. The species of the genus Chcero- 

 campa which Weismann examined, therefore represent three 

 phylogenetic stages of development, and it is interesting that 

 the tropical species are the most advanced ones. It is probable, 

 indeed, of one species, viz., Ch. celerio, that in Europe it shows 

 form c in the markings of its caterpillars, while in India the 

 larvoe of the same species have already attained form d. 



II. In a similar way the author shows that markings upon 

 the larvae of the genus Deilephila, to which the well-known 

 D. eiiphorbi(s (commonly called Sphinx) belongs, have passed 

 through seven phylogenetic stages of development, viz., (i) 

 caterpillars without markings ; (2) with a subdorsal streak ; (3) 

 with a ring-shaped spot upon the last segment but one ; (4) witti 

 similar but not altogether perfect spots upon all segments ; (5) 

 with eleven perfect ring-spots upon the subdorsal streak ; (6) 

 with these ring-spots but without the streak ; (7) with a double 

 row of ring-spots. Nowhere in the development any deviation 

 from this order is noticed, and the living species of this genus 

 form five groups, the markings of their full-grown caterpillars 

 corresponding to the phylogenetic forms Nos. 3 to 7, 



III. A somewhat smaller number of stages of development is 

 apparent in the genera Smerinthus, Macroglossa, Pterogon, 

 Sphinx, Anceryx, which Weismann investigated less extensively 

 than those mentioned before j however, he points out that upon 

 their larvae the simple subdorsal streak combines, in the course 

 of development, with other longitudinal or oblique streaks, or 

 becomes less distinct as the others increase in intensity. 



Now Weismann considers that the remarkable conformities in 

 the development of all the larva markings he investigated is the 

 surest proof that we are dealing with a phenomenon of inherit- 

 ance. Indeed three laws may be said to be established by these 

 conformities, viz., (i) the development begins with the simple 

 and progresses to the more complicated markings ; (2) new 

 markings first appear in the last stage of individual development ; 

 (3) these new markings then gradually pass backwards to the 

 earlier stages and thus replace the older ones, causing them to 

 disappear entirely. Weismann gives the following explanation 

 of the phenomenon referred to in the second law :— Supposing 

 that the respective markings are of use to the caterpillars, that 

 therefore they are retained in subsequent generations by natural 

 adaptation, this use can only be real if the caterpillars are big 

 enough to resemble the different parts of the plants on which 

 they feed, and thus escape being noticed by their enemies ; and 

 if a sufficient lapse of time is given for carrying this protection 

 into effect. Both these conditions, however, are united in the 

 last stage of development, where the caterpillars have attained 

 the necessary size, and which is the longest of all stages. The 

 use of the colour of caterpillars, and the markings upon them, is 

 also perfectly evident. The younger ones are green as long as 

 during the day they remain on the leaves of the plants they feed 

 on ; they do not then form a contrast with the colour of the leavf s 

 themselves. The older caterpillars remain green if the thick 

 foliage of the plants protects them under all circumstances ; 

 if, however, the foliage is less dense, so that the caterpil- 

 lars, as soon as they have grown bigger than the leaves, can 

 be easily distinguished among them, they leave the green leaves 

 in the day-time, and try to hide on the stems of the plants and 

 among withered leaves ; in that case, to complete the protection, 

 their colour changes from green to brown. The biological value 

 of the characteristic markings upon caterpillars, quite inde- 

 pendently of their colour, may be recognised from the fact that 



