2l8 



HARDWICKE'S SCIENCE-GOSSIP. 



grew up till the time came for them to split as their 

 parent did, and thus four cells were produced, and 

 so the process continued, all the young cells sticking 

 together on the principle of co-operation. But co- 

 operation by itself will not produce very great results; 

 it frequently, however, leads to something much more 

 important, and that is the specialisation of function 

 and the differentiation of parts ; here, in the cluster of 

 young amoebas, such a specialisation took place, some 

 became set apart as food providers and agents in 

 locomotion, their pseudopodia becoming converted 

 into flagella, the others served some other purpose, 

 perhaps of secretion, perhaps as storers of nutriment, 

 and perhaps as reproductive agents. So far the corals, 

 sea-anemones, and such-like creatures (Coelenterata) 

 appear to have travelled along veiy much the same 

 road as the sponges, but now they part company; the 

 Ccelenterata originated in the growth of the ciliated 

 cells over the cilialess cells, so that the latter formed 

 the digestive lining inside the resulting gastriila, as 

 we have agreed to call the sac formed by the invagi- 

 nation of the preceding form or blastula ; in the 

 sponges, on the contrary, as we have seen, the 

 ciliated cells withdraw into the cilialess layer, which 

 thus becomes a protecting, instead of a digestive, 

 layer. But now it is worth while recollecting that 

 though this is the normal process with the sponge, 

 yet that the opposite one is frequently passed through 

 as a transitory stage, preliminary to it, and thus we 

 may conjecture that the larva which becomes a 

 sponge now, by invagination of the ciliated layer, is 

 a descendant of a form which used to become a coral 

 by the invagination of the other layer ; that is, that a 

 form on the way to become a Ccelenterate, took the 

 wrong turn for once, and so ended in a cul-de-sac, 

 and became a sponge. Thus the abnormal kind of 

 invagination in Sycandra may be an instance of what 

 is termed " reversion to the ancestral type " ; on the 

 other hand it may simply indicate the balancing play 

 of forces on the young organism, so that it looks as 

 if it could not make up its mind, and was undecided 

 as to whether to turn the flagellated layer inside and 

 become a sponge, or outside, and become a Ccelen- 

 terate. Between these alternative possibilities we 

 cannot decide ; the day has not yet come when the 

 development of an animal may be represented by a 

 mathematical formula, and that wonderful man, the 

 mathematical physicist, has not yet taken the matter 

 in hand. 



To resume our history. The young gastrula, which 

 we beheve to have led an independent life, a free 

 swimmer in the sea, whose parent lived and died a 

 gastrula, took another step in development by be- 

 coming sessile, and here again its contrary disposition 

 was displayed, for instead of settling base downwards 

 as the Ccelenterate gastrula did, when it similarly 

 resigned a free existence, it, on the contrary, attached 

 itself by the mouth, which, by subsequent growth, 

 became obliterated. Hence the origin of pores, and 



the vent which we conventionally call the mouth. We 

 have already stated that some sponges remain their 

 whole life through in the simple stage now reached, 

 giving rise to other sponges, which no more pass be- 

 yond it than their parents did ; yet in the history of 

 the sponges, there must have been a time when one 

 of these simiDle Olynthi progressed a step further, and 

 produced the additional complication of radial tubes. 

 These are simply so many repetitions of the young 

 Olynthus budded out from its sides, and thus again 

 we have co-operation, a number of young Olynthi, 

 remaining attached together to form the wall of the 

 Sycandra. But they all perform the same functions ; 

 the succeeding and more important step, the acquire- 

 ment, by some of the tubes, of one set of functions, 

 and by others, of another, has not yet taken place , 

 some day, perhaps it may ; the future is infinite with 

 possibility, and Sycandra may even yet be destined 

 to a brilliant and successful career. 



THE OLDEST VOLCANO AND MOST RE- 

 CENT LAVA STREAM IN ARGYLESHIRE. 



DURING a succession of summers pleasurably 

 gone, having visited nearly the whole of 

 Argyleshire and southern Perthshire, devoting my 

 energies to the study of the antiquities, rocks, flowers 

 and insects, that I came across ; I should, for the 

 benefit of future tourists, desire to direct attention to 

 certain bold volcanic phenomena that have especially 

 incited my curiosity, and which have doubtless 

 hitherto escaped the attention of specialists, even 

 among those who have tasted the flask and tinnie of 

 mountain water, enjoyed the phantasy of a blanket 

 of Scotch mist, and slept away the sunshine among 

 the crags and ferns of the Highlands. 



Although I have since relearnt my geology on the 

 dreamy shores of the Neapolitan bay, picked up 

 lapilli at Pompeii, and bits of trachyte on the flanks of 

 Monte Nuovo, a mountain so inconspicuous and so 

 unlike the bcaicideal oi Lyell's "Principles," that a 

 looker on naively inquired of me " Where is it ? " 

 although I have since looked out of my window 

 above the olive trees, on Ischia, the home of earth- 

 quakes, and Vesuvius, the abode of fire, until my 

 head, eyes and pencil, were fairly wearied out — for all 

 such machinery and world manufacture of beautiful 

 Parthenope and her land of labour, give me to enjoy 

 that grandeur of conception that arises when the all 

 silent hills of Arran and smokeless cones of Jura 

 first loom on the sea mist. 



This undefinable feeling of majesty and isolation 

 akin to that experienced wdien the earth turns its side 

 to the starry vault without, is mainly due to a con- 

 ception of the lapse of time ; and it springs equally 

 in the breast when we turn our regards to the glacial 

 phenomena of Caledonia. What, after all, is the 



