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SCIENTIFIC NEV\^S. 



[Mar. 1 6, iSSS. 



period a beak-shaped organ is placed at about a right 

 angle with the main portion of the valve ; it is pointed 

 at the extremity, and bears numerous sharp spines. 

 After the shell has been formed, a new structure makes 

 its appearance, known as the byssus-gland, which secretes 

 an elongated cord by which the larva^can suspend itself. 



With the development of the shell, the mantle and the 

 sense organs, the young mussel reaches its full larval 

 development, and is now known as a Glochidium. 

 These glochidia are very unlike the parent, so that when 

 first discovered, they were thought to be parasites. They 

 are very numerous during the winter months, being 

 found in the branchia; or gills of the parent, which have 

 been compared in this respect to the " marsupium " or 

 pouch of the marsupial animals — as the kangaroo, etc. 



During the spring the parent ejects these larval 

 glochidia, and when a fish swims by they attach 

 themselves to the gills, fins, or other parts by 

 means of the spinous processes, and then affix 

 the byssus cord ; they then become covered over by the 

 growth of the epidermic cells, or skin of their host, and 

 undergo a metamorphosis. While in this condition they 

 can be carried for miles away by their host in its travels; 

 this may probably explain the world-wide occurrence of 

 freshwater mussels. 



The first change that occurs is the disappearance of 

 the byssus and byssus organ ; shortly afterwards all 

 traces of the sense organs become lost. The anterior 

 and posterior adductor muscles now form at the two 

 ends of the body. The mantle lobes then undergo 

 great changes ; and according to Braun, the permanent 

 shell is formed on the dorsal surface of the parasitic 

 larva in the form of two small independent plates. By 

 the time the larva, or, as it is now, the young mussel, 

 leaves its host, all its parts, with the exception of the 

 generative organs, are developed. It then drops into the 

 mud at the bottom of the water, wherever it may have 

 been carried, and commences life independently. 



This example of transformation undergone by the 

 freshwater mussel is of particular interest. The changes 

 or transformations which the young mussel undergoes 

 are, in reality, the changes which have been brought 

 about during very long periods of time, extending far 

 back into geological ages. That the changes in the 

 young are the abbreviated history of the organism is 

 now generally accepted as a truth, and we learn from 

 this that the ancestors of modern freshwater mussels 

 probably lived in marine surroundings, had shells 

 like the glochidium^ and were attached by means of the 

 byssus to a rock like the marine mussels. By some 

 means or other, some specimens were introduced into 

 freshwater, verj' probably by their attachment to some 

 floating object. The modifiability of an organism is 

 always at a tension when introduced into another 

 element, and this change in the surrounding medium 

 of the ancestral form brought about modifications in the 

 structure of the animal and its shell, the transforming 

 influence of the fresh waters in which it found itself 

 having left their traces after a lapse of ages in the para- 

 sitism and metamorphoses of the young mollusc. 



Freshwater mussels are a very ancient family, having 

 come into existence at a very early stage of the world's 

 history. During the period when our coal beds were 

 being formed they were very abundant in the swamps 

 which then existed ; they have undergone many vicissi- 

 tudes, and seen many changes in our earth. They have, 

 however, survived, and live to tell their tale of evolution. 



OLD ANTS AND AGED SPIDERS. 

 Dr. H. C. McCook, in an interesting paper lately 

 read before the Philadelphia Academy of Sciences, 

 and reported in the Ledger, gave an account of the life- 

 history of a fine specimen ot the spider, commonly 

 known as the American tarantula. The animal was 

 given to him in 1S82, by Dr. Joseph Leidy. It was then 

 apparently eighteen months or two years old, and it 

 lived in captivity until July, 1887. At the period of 

 its death, therefore, it must have been at least seven 

 years old, and may have been eight, having thus 

 attained the distinction of being the most aged spider 

 known to science. How long this species and other 

 spiders generally live in their natural habitat is not 

 known, but human protection in the present instance 

 probably aided to prolong life. It was kept first in a 

 glass globe, and afterwards in a wooden box, with glazed 

 sides and a sliding glass door at the top. One end was 

 filled with dry soil, which was slightly compacted and 

 heaped up. The other end was sparsely covered with 

 earth. It was at all times liberally supplied with water, 

 and its food consisted of live flies, grasshoppers, and 

 locusts. During confinement the tarantula shed its Skin 

 several times, a process apparently attended with some 

 danger, as it was during such a change the creature 

 died ; and once before, on a similar occasion, it was 

 found apparently dead, although it afterwards 

 revived. It is possible that it was too much 

 exhausted by a long previous fasting to endure 

 the severe strain which evidently is laid upon the 

 organism in the act of moulting. The spring of 1887 

 was a backward one, and some difficulty was experi- 

 enced in procuring insects for food from the immediate 

 neighbourhood. The annual supply of grasshoppers 

 and locusts was very late, and it may be that, had the 

 spider been strengthened by a few weeks' generous feed- 

 ing previous to its last moult, it might have been still 

 alive. 



In connection with the general subject of the pro- 

 longed life of insects. Dr. McCook stated that during a 

 recent visit to Sir John Lubbock, at his house in London, 

 he inquired after a queen of the fuscous ant, which he had 

 seen in an artificial formicary six years ago, it being 

 then nearly eight years old. He was told by his host 

 that it had died the day before, having at the time 

 reached the wonderful age of more than thirteen years. 

 She was still attended by her circle of courtiers. Some 

 of these were licking the dead queen, or touching her 

 with their antennae, and making other demonstrations 

 as though soliciting her attention, or desiring to wake 

 her out of sleep. It was certainly a touching sight to 

 witness these faithful attendants surrounding the dead 

 body of one who had so long presided over the maternal 

 destinies of the colony, and seeking by their caresses to 

 evoke the attention which never again could respond to 

 their solicitations. 



The Largest Oak in Germany. — The Neue Previssiche 

 Zeitung announces that this tree grows in the manor of 

 Kadien, two miles to the north of Elbing, on the Frischer 

 Haft". The mean circumference of the stem is ten yards. 

 It is hollow, and the interior is closed with a gate. The 

 cavity is so roomy that a class of thirty-five boys of 

 eleven and twelve years of age belonging to a neighbour- 

 ing school were able to crowd into it at once. The tree 

 puts out yearly a luxuriant crop of leaves. 



