Nov. 1, 1866.] 



HARDWICKE'S SCIENCE-GOSSIP. 



213 



The way this sac is, as it were, folded, and the 

 different compartments made for the accommodation 

 of the embryonic fish, is most singular, and very 

 difficult to discover clearly. The best illustration I 

 can think of is an orange. You must imagine the 

 orange divided into rits proper number of little 

 wedge-shaped pieces, and each piece to represent a 

 fish ; that the rind of the orange is a delicate 

 membrane, having a globular shape, and easily 

 compressed or folded. You now desire to fit the 

 pieces together again into the original orange-shape. 

 You must begin on the outside of the globular 

 membrane, pressing in with each section a fold of 

 membrane (remember that each represents a fish), 

 when each piece is in its place you will still have the 

 sac in its rounded form, but the rind representing 

 the membrane has been folded in with the different 

 pieces. 



If I have made myself understood, it will be 

 seen that there must be a double fold of membrane 

 between each portion of orange. This is exactly 

 the way the fish are packed in this novel placental 

 sac. If it were practicable to remove each fish from 

 its space and the sac retain its normal shape there 

 would be twelve, or fourteen openings (depending on 

 the number of young fish), the wall of each division 

 being a double fold of membrane, the double edges 

 wrapping, or, as it were, folding over the fish. Now 

 make a hole in the end of the bag and Mow it full 

 of air, and you get at once the globe-shaped 

 membranous sac I have likened to an orange. 



Again and again have I dissected out this ovarian 

 bag filled with fish in various stages of develop- 

 ment, and floating it in salt water, have, with a 

 fine-pointed needle, opened the edges of the double 

 membranous divisions which envelop the fish (the 

 amount of overlapping is of course greater when 

 the fish is in its earlier stages of development), 

 on separating the edges of the sac, out the little 

 fishes pop. I have obtained them in all stages of 

 their growth, but sometimes (and this not once or 

 twice, but often), have set free the young fish from 

 its dead mother ; thus prematurely cut loose from 

 its membranous prison, the young, enjoying its 

 newly-acquired liberty, swam about in the salt 

 water, brisk, jolly, and as well able to take care of 

 itself as its parent. 



The most beautiful of all the species (for a de- 

 tailed list of which vide "Naturalist in Vancouver 

 Island and British Columbia," vol. ii. Appendix, 

 page; 353) is the sapphire perch (so called by the 

 traders), very plentiful in Puget's Sound. Eighteen 

 exquisitely beautiful mazarine-blue lines mark its 

 entire length from head to tail, and above and below 

 this line are a number of spots of most dazzling blue, 

 arranged in a crescent shape about the eyes and gill- 

 covers. Between these spots the colour changes, 

 as it does in the dolphin, throwing off a kind of 

 phosphorescent light of varying shades of gold, 



purple, and green. The back bright-blue, but darker 

 than the stripes; the belly white, marked by streaks 

 of golden yellow. J. K. Lord, E.Z.S. 



THE GLOWWORM (Lampyris nodilucd). 



T?EW who have rambled through green lanes in 

 -■- the evening can have failed to notice this little 

 light-giver, and wondered at the cause of the flood 

 of radiance emitted by so small an insect ; for 

 though the light-producing Lctmpyridce and the 

 luminous insects of other orders have attracted the 

 attention of many celebrated naturalists, a perfectly 

 satisfactory theory has not, so far as I am aware, 

 been offered to account for this curious pheno- 

 menon,* which, though termed phosphorescence, 

 seems, from its steady continuance and the control 

 the animal has over it, to differ from the evanescent 

 shining exhibited by some of the Acaleplue (Sea- 

 nettles), and by decomposing animal and vegetable 

 matter. Be the cause of the light what it may, 

 there can be little doubt respecting its object, 

 which is evidently to attract the males--an idea 

 prettily expressed in the following lines by Moore :— 



" Beautiful as is the light 

 The Glowworm hangs out to allure 

 Her mate to her green bower at night." 



Some naturalists have disputed this opinion on the 

 ground that the males themselves are slightly 

 luminous, and they therefore think it has probably 

 some use disconnected with the union of the sexes. 

 But this may be only an illustration of a principle 

 very commonly observed in Nature — that of one 

 sex having rudiments of organs which only reach 

 their full development in the opposite one; for 

 example, the female of the pretty gold-tailed moth 

 (Liparis auriflua) has a thick mass of hair at the 

 extremity of the abdomen, which is plucked off by 

 the moth, and used to cover her eggs, and so secure 

 them from rain or excessive heat. This [is repre- 

 sented in the male by the elegant fringe of golden 

 hairs which gives the trivial name to the species. It 

 may be worthy of remark that in those species of 

 moths which have apterous or very sluggish females, 

 the males are generally provided with large plumose 

 antennae, which are evidently delicate organs of 

 sensation, and enable them to discover the females 

 even when separated by long distances. The Glow- 

 worm, on the contrary, has very simple antennae, 

 and may require some other aid to guide it in its 

 amorous expeditions. I have had abundant evidence 

 of their light-seeking propensities when insect- 

 hunting with a lanthorn in some of the Kentish 

 woods, and have frequently seen dozens settle on 

 my clothes, or dash against the glass, in the course 

 of a single evening. 



See " Popular Science Review ' 



for July, l 

 M 2 



