HARDWICKE'S SCIENCE-GOSSIP. 



179 



may in some measure owe their existence to the 

 •stunted and sparse vegetation of these bleak situa- 

 tions. 



Turning from a consideration of the wings to the 

 mutation of the parts of the body, we find that these 

 either participate in the diminution when the species 

 may be termed a true dwarf, or that they have their 

 usual dimensions while the wings alone have been 

 arrested in expansion : examples of either process 

 are common enough in most cabinets. The tortoise- 

 shell butterfly has yet another remarkable mark of 

 evolution in common with its tribe, to be found in 

 those tassel forelegs that hang down like grass tails 

 in front, and which, similarly to the feet of a Chinese 

 beauty, give good evidence of being diverted from 

 their true use. This cramping and abbreviation of 

 the member is not, however, like wing expansion 

 dependent on climate, as is rendered evident from 

 the wide dispersion of these old soldiers over the 

 earth's surface ; neither as in the possible case of 

 a tiger moth bred from lettuce dipped in chalk and 

 water, which emerged with the merest rudiments 

 of feet or tarsi to the forelegs, and with the articu- 

 lations of the second pair soldered together ; can this 

 be the result of a particular soil ? No, ridiculous 

 though it may appear to us short-sighted mortals 

 who see not the days of the elephant or swan, it yet 

 rests on common observation, that when certain 

 Lepidoptera settle for long together on the ground, 

 they rest on their four hinder legs, and raising the 

 front pair, allow them to dangle down, so that 

 muscle and nerve may never in the lapse of centuries 

 be brought into play. Of all butterflies, none are 

 more conspicuously sedentary than the tortoisehells 

 that sun themselves on our roads and garden blossoms 

 the livelong day, and no old cripples, therefore, if 

 these premises be correct, can afford better example 

 of the punishment of effeminacy in the war with the 

 environment. 



RECREATIONS IN FOSSIL BOTANY. 



Reproductive Organs of Lepidodendroid 



Plants. 



No. V. 



By James Spencer. 



THE Halifax coal-balls [have yielded a great 

 variety of other coal plants besides Lepidoden- 

 drons and Sigillarias, some of which I hope to 

 describe on future occasions, but perhaps their most 

 interesting novelties consist in the abundance of 

 cones, sporangia, and spores, and other reproductive 

 organs, found therein — the very parts of fossil 

 plants which are so often wanting. 



The fossil ferns, for instance, which are said to 

 form one-third of the total number of species of fossil 



plants and which are so profusely scattered up and 

 down the shales, sandstones and ironstones of car- 

 boniferous age, are generally devoid of all traces 

 of fructification. I am aware that Lyell, in his " Ele- 

 ments of Geology," mentions the finding of fossil ferns 

 in Coalbrookdale, and in Maryland in America, having 

 the markings of the sori plainly to be seen. But in 

 these Halifax coal-balls the annulus of fossil ferns, 

 often containing spores, are found in great profusion, 

 and as beautiful and perfect as those on the back of 

 recent ferns. There are two kinds of lepidodendroid 

 spores, one being very much larger than the other, 

 and is called the macrospore or female (fig, 108), 

 and the other one is called the microspore or male- 

 spore (fig. 109). 



The macro- and microspores are not all alike, they 

 most probably vary according to the species of plants 

 to which they belonged, yet they have all a great 

 family likeness. They are sometimes found enclosed 

 in little bags, which are termed sporangia, and these 

 sporangia are also sometimes found in a cone, called 

 lepidostrobus. A perfect cone therefore contains 

 sporangia, and these again contain the spores. Some 

 sporangia contain macrospores only, others contain 

 only microspores. The microsporangia, both in the 

 fossil cones and in the modern representatives, are 

 generally situated at the upper part of the cone, while 

 the macrosporangia occupy the lower part ; but there 

 are important exceptions to this rule in both the 

 recent and fossil state. In our coal-balls we meet 

 with a great number and variety of both macro- and 

 microspores ; the most common macrospore is a com- 

 paratively large one, being about j'g in. in diameter. 

 (Fig. 108.) It is covered with hair-like appendages 

 which, in transverse sections, form a beautiful fringe 

 around the spore. These caudate appendages occur 

 both single and branched, and are simple prolongations 

 of the thick spore-wall. 



We frequently find these macrospores containing 

 small bodies called endospores, which are almost 

 always round in form, but by no means uniform in 

 size ; some macrospores containing a few large 

 endospores, others containing a large number of 

 small ones, others again containing both large and 

 small ones. 



One of my sections shows a macrospore, which 

 contains a number of these endospores, most of which 

 are again enclosed in mother spores. What these 

 small bodies are, I will leave for other and better 

 qualified writers to say. I have macrospores con- 

 taining a network of cellular tissue which is the 

 nearest approach to a true prothallus that I have seen 

 in connection with them. 



The normal number of macrospores in each 

 sporangium is four, but they are rarely met with 

 enclosed in a sporangium ; when such is the case, 

 three macrospores only are visible, though sometimes 

 a small portion of the fourth can be seen. The 

 reason why we only see three spores in any section is 



