HARD WICKE 'S SCIENCE- G OS SIP. 



us that they are " of a very pale light blue, marked 

 with faint tinges of light purple, and long straggling 

 lines and dashes of black." The Stitrnus predatorius 

 is very common with us, and up our lakes hundreds 

 of them may be seen of an evening on the rush- 

 beds, just as I have seen the common starlings in 

 England, where I have killed a dozen or more at a 

 shot. 



While submitting my notes on the parasites of the 

 Colorado Beetle, it occurs to me that perhaps a few 

 more instances of the principle of compensation may 

 not prove uninteresting. 



We have in Canada a great variety of Ichneumon- 

 flies, from the large Pimpla lanator, with its four- 

 inch borer, to the Ichneumon minntiis, each in its 

 own peculiar way, whether by piercing the living 

 insect, or its egg, doing its providential work in the 

 destruction of hurtful life. 



Some time ago my eye was attracted by the eccen- 

 tric motions of one of the larger steel-blue Ichneumons 

 that was flying round and round a currant-bush in 

 my garden, ever and anon darting at an object which, 

 on approaching it, I found to be a spider in her web. 

 The contest, for such it was, was a long one, and 

 put me in mind of the description of an arena-fight 

 between a retiarins and a sccutor. The latter, on 

 this occasion, was victorious : the rete proved an in- 

 sufficient protection, and the fuscina, or ovipositor, 

 was thrust into the victim's body, with what result is 

 well known to naturalists. 



On another occasion I saw one of our larger grass- 

 hoppers, Locusta Carolina, struggling in apparent 

 agony and certain helplessness on the ground. On 

 examination I discovered a small ichneumon, not 

 much larger than a winged ant, upon its body, intent 

 on the insertion of its ovipositor, and although the 

 fly was so much smaller and so much weaker than 

 the unhappy grasshopper, the latter was unable to 

 make use of its powerful legs or its wide expanse of 

 wings as a means of escape. 



Another singular parasite, if parasite it may be 

 called, is the Hair Worm, Gonlins. I once obtained 

 two of these Abranchiata from the body of a large 

 spider — a somewhat uncommon habitat. These 

 worms were tightly rolled up into small balls of the 

 Gordian-knot type, and were, when unfolded, only 

 about two inches each in length. 



At another time I found one of our common 

 crickets, the Acheta abbreviata, with a Hair Worm 

 curled around it. Whenever the miserable insect 

 made an effort to release itself from the coils of its 

 tormentor the latter lashed itself into apparent fury, 

 and seemed to paralyze its victim until at length it 

 accomplished its horrible design. 



Are these egg-depositing operations painful to the 

 subject ? It would be interesting if observers would 

 state their opinions, and give us the results of their 

 observations, on this interesting subject. 



Ontario. V. Clementi, B.A. 



223 



SOME REMARKS ON HORSE-TAILS. 



THE Horse-Tails compose the order Equisetaccce, 

 and this order of Cryptogams is a very inte- 

 resting one, both as regards the structure of the plants 

 contained in it, and the curious hygrometric move- 

 ments of their spores. 



The stem is underground, and in the spring sends 

 up branches, some of which are barren, while others 

 bear the spores. The branches are hollow, except at 

 the joints, which are numerous ; at these points the 

 different segments of the stem are separated by a 

 sort of cellular membrane. Each joint likewise 

 terminates in a sheath, which is membraneous, and 

 embraces the base of the succeeding joint. The 

 branches are fluted, and the sheath at its upper 

 extremity is cut into teeth, the number of which 

 corresponds, or bears some simple proportion, to the 

 flutings on the stem. 



These plants are devoid of true leaves ; but the 

 latter are represented by branchlets, which are of a 

 green colour, and often assume a verticillate arrange- 

 ment. A very interesting microscopical object is 

 furnished by the cuticle of the Horse-Tail — the sto- 

 mata being seen with great clearness under a mode- 

 rate power. The epidermis is likewise peculiar, on 

 account of the large quantity of silex which it con- 

 tains ; this is so abundant in many species that they 

 have been used by the Dutch housewives for polishing 

 brass. 



The most interesting points, however, about these 

 plants is their fructification. All the branches are 

 not fertile, but those that are bear at the terminal 

 extremity a cone-like body, which, on examination, 

 is found to consist of a great number of disks, more 

 or less polygonal in outline, borne in a peltate 

 manner upon a central stalk, by which they are 

 attached to the central axis. On the under surface 

 of these disks the spore-cases are arranged, and these 

 discharge their contents (the spores) by a lateral slit, 

 which looks towards the axis of the plant. The 

 spores themselves are more or less rounded bodies, 

 each provided with two filaments called elaters, and 

 to the contraction and expansion of these the move- 

 ments of the spores are due. The elaters end in 

 club-shaped extremities. If the end of a branch of 

 Equisetum bearing fructification be shaken gently on 

 to a glass slide, and the latter be then breathed upon, 

 and placed upon the stage of a microscope of low 

 power, the spores will be seen to be undergoing the 

 most curious movements. Some will be quite closed 

 up, the elaters being so closely applied to the spores 

 as to be scarcely distinguishable ; others, again, will 

 be seen gradually unfolding the filaments, and a few 

 may be observed to move with a sudden start, as it 

 were, from the contracted state of the elaters to that 

 of full expansion. The ultimate cause of this move- 

 ment is quite unknown. That it depends upon the 



