358 



KNOWLEDGE 



[JcxE 15, 1883. 



very rare among Catholics, who formtil three-fourths of 

 the population of Ireland. Tiie general conclusion arrive,d 

 at was that consanguiaeous marriages was a cause of deaf- 

 mutism. 



The Chairman (Dr. Fitzpatrick) observed that the paper 

 was the most remarkable he had heard at any public meet 

 ing for a long period, making it apparently clear to d(Mnon- 

 stratiou that the marriages, particularly of lirstand second 

 cousins, were productive of deaf mutism. In his own 

 long experience he found almost every case of deaf-mutism 

 to be the result of the intermarriage of near relatives. 

 To take an example, he found not only was one child a 

 deaf-mute, and another insane, but the whole family partook 

 of degeneration of the nervous power. They entered early 

 into marriage and never prospered in society. Scrofula, 

 deaf-mutism, insanity, and other characteristics exhibiting 

 weakness of lirain and muscular power resulted from those 

 marriages. 



Dr. Eustace thought the question must be considered 

 very much from the animal point of view. The human 

 family was at the head of all other animals, so that the 

 question might be elucidated by what took place M'ith other 

 animals, who, according to their anatomy and in many 

 respects, were our relatives. It was well known to all 

 persons who tried to breed first-class animals that close 

 in-and-in breeding resulted in very great deterioration of 

 the species, and also that animals, when left to themselves, 

 did not select their nearest relations for sexual intercourse. 

 That intermarriages were productive of many evils as a 

 general result he held to be a fact. With regard to mental 

 disease, he believed the health of the intellect in the 

 human family depended more largely than they were in the 

 habit of considering on the bodily health or physique, 

 although there were exceptional cases in which very poor 

 specimens of humanity were gifted with brilliant intellect. 

 In the treatment of the insane his leading principle was 

 to get up the bodily health, and as it improved the mind 

 improved. 



Dr. Cox mentioned an instance in which two cousins got 

 married. Both were healthy, and without any special 

 indication of disease. The result was, that of the oft- 

 spring, one, a very tine girl, died of phthisis, another 

 developed symptoms of lung disease, but happily escaped 

 consumption, and a third developed spinal disease. Again, 

 in animals other than the human species, disease was 

 apt to occur in those nearly related ; while in the vegetable 

 kingdom, plants of the same kind which were barren were 

 often fertilised l)y the pollen of others. 



Dr. Willis instanced a case he saw some years ago near 

 London, of a sick child whose father and mother were deaf 

 and dumb, and it was through their children, all of whom 

 could speak, he came to a decision about the ailment. 



Dr. Wright concurred as to the damage ensuing from 

 the marriage of near relatives, and referred to Darwin's 

 experiment on pigeons, and to the difficulty of keeping a 

 pure breed of poultry, as illustrated by the fate of the 

 bantams brought from the palace of Pekin, and by the 

 destruction of another favourite breed of fowls, the 

 white-crested Polish. 



The President replied, pointing out that his statistics 

 ■were necessarily incomplete and restricted. It would be 

 indispensable to ascertain how many of the whole popula- 

 tion were the children of first cousins before drawing a 

 definite conclusion. 



PLEASANT HOURS WITH THE 

 MICROSCOPE. 



By Henry J. Slack, F.G.S., F.R.M.S. 



rpHE present is an excellent time for Rotifer-hunting. 

 A. A pond, in a sunny situation, covered with a green 

 scum caused by myriads of minute vegetable organisms, is 

 sure to contain several species; while other ponds and quiet 

 river pools, in which various flowering water-plants grow, 

 are likely to be frequented by the tube dwelling species 

 which attach themselves to the stalks or leaves. There are. 

 three obvious distinctions amongst groups of rotifers. There 

 are two sorts of free swimmers ; to the first of these belonga 

 the Philodines, of which the common rotifer, Ji. rvlgaris, 

 is tiie most abundant. All members of this group are 

 protected Viy a strong skin, and as it is very elastic, and 

 has its telescope-like joints united by a flexible material, 

 they can execute very curious changes of form. Sometimes 

 one will be nearly globular ; at others every joint stretched 

 out, and thecreature worm-like in shape, with a conical snout. 

 Suddenly, this snout is withdrawn, and the rotary organs 

 protruded, which work so as to produce the optical illusion 

 of wheels revolving on an axis (Fig. 1.) The second sort 



Tramways in Japan. — A tramway is now in operation 

 at '] okio, the capital of Japan. The traffic is stated to 

 be making satisfactory progress. 



1. Rotifer Vulgaris. A, irs so-called gizzard ; B, contractile 

 vesicle connected with the water vascular system. 



of free swimmers are provided with a carapace, or hard, 

 transparent shell, to which they are organically attached 

 at certain points, but so as to permit their bodies to enjoy 

 consideralile freedom of motion inside their armour (Fig. 2). 

 After these may be ranged the householders, or tube- 

 dwellers — a most interesting group (Fig. 3). Their usual 

 plan is to throw ofl' rings of a gelatinous substance. These 

 arranged one upon another, and kept hollow by the motions 

 of the creatures while they are consolidating, form con- 

 venient dwellings. One species makes a great advance in 

 construction, and is the architect of the family ; this is the 

 ilfelicerta ringens, which is provided with a brick-monld- 

 ing apparatus, and builds her house by placing brick upon 

 brick in workmanlike fashion. There are also rotifers that 

 dwell in societies, like Coiioccliibis, a mass of gelatinous 

 matter forming their common home. 



It is well to begin with some general notions of the 

 rotifer tribe, as no one can foresee what is likely to be the 

 result of a few hours' search after them. A few differ 

 very widely from the typical genera, but in all the above- 

 mentioned an apparatus of cilia producing whirlpool 

 currents may be observed, though they do not all exhibit 

 this in the wheel-like shape. The rotifer-hunter should 

 be provided Mith a wide-moutlied bottle at the end of a 



