HARD WICKE ' S S CIE NCE - G SSIP. 



3i 



Rothwell and Howarth called in to observe the 

 organisms. The next day they placed a fresh drop 

 of the serum on the stage, and found the microbes 

 far more numerous than previously. About two 

 hours later Mr. Midgley noticed a change in one of 

 the inactive, opaque specks already referred to, and 

 shortly after the whole " field " was filled with fine 

 dust-like granules. Half-an-hour later this had 

 visibly begun to thin away, and upon careful illumi- 

 nation he could see the whole mass dancing about 

 with the energies of vital force ; and in a period of 

 3^ hours from the time of observing the first change 

 of the test bursting, the granules had become as 

 active, and of the same shape, as the adult bacilli. 

 He then concluded that the opaque specks noticed 

 were encysted forms, and, having undergone seg- 

 mentation, burst, and discharged their spores. They 

 could readily see the binary fission going on in the 

 rod-like forms, by the deepening of the constrictions, 

 and, first assuming the dumb-bell shape, then separate, 

 and become two distinct individuals. The serum 

 was kept under cultivation for several clays, and the 

 alternation of generations watched from time to time. 

 In order to see how the bacilli could be cultivated in 

 milk, five drops were placed in a gill of new milk at 

 10 a.m. At 7 P.M. a drop of it was examined, and 

 found to contain such a vast number moving among 

 the fat cells of the milk as to keep the smallest cells 

 in constant movement. The rapid rate of increase 

 proved how enormous is their power for evil if the 

 virus be introduced into the dairy. The next morning 

 the milk had become slightly sour, and contained 

 very few moving forms. By noon it had become 

 white opaque, and was destroyed. Another of the 

 experiments brought out how tenacious of life the 

 microbes are. Three drops were placed in a small 

 test-tube with about half an ounce of water, and held 

 over a spirit lamp to boil for five minutes. The 

 water was corked up while cool and examined, and 

 to their astonishment they found them moving about 

 the " field " as if nothing had happened. The intro- 

 duction of alcohol or dilute sulphuric acid at once 

 arrested their movements. In conclusion, he said 

 that the presence of bacilli having been found in a 

 region of the body so remote from the viscera as the 

 brain, entirely disposed of the doubt honestly held by 

 Klein, and he thought entirely settled the question, 

 not only that Messrs. Klebs and Eberth were on the 

 right track, but that typhoid lever is accompanied 

 by these minute poisonous organisms. The great 

 problem which science had to solve was, whether it 

 was possible to modify the virulence of this noxious 

 bacillus into the innoculo-septic form of Bacillus 

 subti/is, as Biichner claims to have done with the 

 Bacillus anthrax of splenic fever. 



Dr. Samuel Birch, Keeper of the Egyptian and 

 Oriental antiquities in the British Museum, has died 

 at the age of seventy-two. 



TEMPORARY ENCYSTMENT AMONG 

 INFUSORIA. 



LAST summer I made an infusion of hay, which 

 presently swarmed with Hypotrichous In- 

 fusoria, which were either of the genus Stylonychia, 

 or some closely allied genus. I spent a good deal 

 of time in watching their habits, which proved to 

 be of great interest, and intended to determine the 

 species more accurately later on. I failed to do so, 

 however, because after a while a few of them began 

 to form cysts (Fig. 24), covered with large strong 

 projections ; and the rest followed suit so rapidly that 

 in forty-eight hours I had not a single free individual 

 left. I shall in this paper call them Stylonychia ; 

 but it must be borne in mind that I am by no means 

 certain that this is correct. None of them left their 

 cysts before I had to go away from Devonshire. 

 These strong spiny cysts are formed to protect them 

 during a resting period. In what form they emerge 

 from the cyst I cannot tell, but probably in their 

 original form. I did not notice any particular 

 abundance of conjugating individuals while the en- 

 cystment was going on. Stylonychia Pustulata forms 

 a cyst figured by Stein (Sav. Kent, pi. 45, fig. 16), 

 which is very like those which I found, but differing 

 in one respect. In 6". pustulata the spines are 

 generally united at their bases, whilst in those which 

 I found the spines rarely touch each other, and are 

 often separated by a space equal to half or more than 

 half their height. These cysts seem to be simply 

 protective, and are formed when the surrounding 

 conditions are unfavourable, such as change of 

 temperature, or the drying up of the ditch, or other 

 water they are in. When thus encysted they are 

 often blown about by the wind, and so, as all In- 

 fusoria-hunters know, turn up in places where they 

 were not known before. 



Amongst the Stylonychias were a large number of 

 Tentaculiferous Infusoria, belonging to the genera 

 Sphserophrya and Podophrya. These Infusoria have 

 clubbed tentacles, through which they suck the juices 

 of their prey. It is the relation between these and 

 the Stylonychias which I have to describe. 



Several of the Stylonychias were observed swimming 

 about with a Sphaerophrya attached. It was obser- 

 vations similar to this which led Stein to form his 

 celebrated theory, that the young of many Infusoria 

 were of the Acineta or Tentaculiferous type. Cla- 

 parede and Lachmann, however, soon proved that 

 the Acineta form was a parasite, and not the off- 

 spring ; and Stein has since abandoned his theory. 

 In one of these cases I observed a very singular fact 

 - — the Sphaerophrya had its clubbed tentacles extended 

 to their usual length ; but it was also provided with 

 a very large number of short tentacles, which were in 

 constant slow, wavy, or vibratory motion (Fig. 25). 

 They were much too thick to be called cilia, other- 

 wise the case might be held to be parallel to the 



