3 o8 



SCIENCE-GOSSIP. 



Euglena viridis, and even there it might have been 

 present and escaped my notice. It was described 

 by John Harris, in 1696, from whose writing the 

 following extract is taken : 



"April 27th, 1696. — With a much better micro- 

 scope I examined some rain-water that had stood 

 uncovered a pretty while, but had not contracted 

 any such thick and discoloured scum as that 

 before mentioned had. A little thin white scum, 

 that like grease began to appear on the surface, 

 I found to be a congeries of exceeding small 

 animalculae of different shapes and sizes. At 

 the same time I look't on a small drop of the 

 green surface of some puddle water which stood 

 in my yard. This I found to be altogether 

 composed of animals of several shapes and mag- 

 nitudes. But the most remarkable were those 

 which gave the water that green colour, and 

 were small oval creatures, whose middle was of a 

 grass green, but each end clear and transparent. 

 They would contract and dilate themselves, tumble 

 over and over many times together, and then shoot 

 away like fishes. Their head was at the broadest 

 end, for they still moved that way. They were 

 very numerous, but yet so large that I could dis- 

 tinguish them very plainly with a glass that did 

 not magnify very much." 



The observations of John Harris were, as far as 

 they went, exceedingly accurate, and more recent 

 observers working with better optical appliances, 

 although of course they have amplified his obser- 

 vations to a considerable extent, have not been 

 obliged to contradict them. 



Eugiena viridis, Ehr., is fusiform in shape and 

 42 to 170 microns in length ; the anterior end is 

 blunt, as stated by John Harris, and the posterior 

 end is more or less pointed ; the outside surface is 

 marked by , oblique striae ; there is a conical 

 depression at the anterior extremity, at the base of 

 which is situated the mouth, and from which 

 springs a slender flagellum exceeding the body in 

 length. It is by the lashing of this organ that the 

 animal is enabled to "shoot away like a fish." 

 The creeping and crawling movements are brought 

 about by peristaltic contractions of the body, 

 something like those of a short worm. These 

 movements are so characteristic that they have 

 been termed " euglenoid." 



The central portion of the endoplasm is coloured 

 bright green owing to the presence of chlorophyll. 

 This is said by Savile Kent to be assimilated, but 

 Jeffery Parker states in his " Elementary Biology " 

 that it acts in the same way as the chlorophyll of 

 plants, which would hardly be the case unless the 

 chlorophyll were developed by the animal itself. 

 This green colouring matter is not invariable, and 

 is stated on some occasions to turn to dark orange 

 or red. 



There is one contractile vacuole situated 



anteriorly which opens into a reservoir, and in 

 this part of the body also the red eye-like pigment 

 spot or stigma is to be found. The nucleus is 

 sub-central in position and possesses a well-marked 

 nucleolus. Round it are arranged the highly 

 refractive amylaceous corpuscles. These are 

 composed of a substance known as amylum, which 

 is an organic compound built up of the same 

 elements — namely, carbon, hydrogen and oxygen — 

 united together in the same proportions as starch, 

 but in a slightly different way. Amylum does not 

 form a blue compound with iodine, which is a 

 reaction characteristic of starch. 



Under certain conditions Eugiena loses its flagel- 

 lum, settles down to rest, and develops a coat of 

 cellulose round it. If the conditions are favourable 

 it emerges from this after a period of rest, and 

 resumes active life again. Reproduction takes 

 place either by the simple fission of the resting 

 form, or by the formation of spores from it. In 

 the latter case, when the cyst is ruptured, a 

 number of small, green creeping things, like 

 amcebse are released, without mouth, gullet 

 or flagellum. All these organs are gradually 

 developed, and the adult form again presents 

 itself to us. A third form of reproduction is 

 described by Stein. This is brought about by 

 the abnormal growth of the nucleus, which finally 

 breaks up into numerous spores ; these spores are 

 liberated during the life of the parent as minute 

 monadiform germs. A similar process of re- 

 production is described by the same authority as 

 occurring in the genus Trachelomonas. 



Eugiena descs, Ehr. — This species differs from the 

 last in shape, being not fusiform but cylindrical 

 and very wormlike; it may be from fifteen to 

 twenty times as long as broad, and when fully 

 extended is acutely pointed posteriorly. However, 

 it is very seldom fully extended, and is most often 

 seen with one part of the body contracted into a 

 lump. Ehrenberg, who was the first to describe 

 it, affirms that this species never swims, but 

 confines its movements to sluggish creepings and 

 twistings. 



It may be found in ponds overgrown with 

 duckweed, but is never taken in such large shoals 

 as is E. viridis. The length of the body is from 

 36 to no microns. 



Eugiena acus, Ehr. — This species almost might 

 be said to represent the transition between Eugiena 

 and Phacus. Their " deportment in water " is, 

 according to Savile Kent, " remarkably stiff, " and 

 they do not exhibit protean contractions and 

 expansions like the other species of the genus. All 

 this points to the fact that the cuticular surface is 

 firmly developed, which, it will be seen, is one of 

 the characteristics of Phacus. The body is slender 

 and elongate, from seven to eight, to ten or twelve 

 times as long as broad, tapering towards the 





