March 1, 1899.] 



KNOWLEDGE. 



51 



this time of day one may be bitten more than a hundi-ed 

 times, while throughout the rest of the day and night not 

 five bites may be received. The second species bites more 

 at twilight than at any other period of the day, as does 

 also Cuh-x malaritr. All these facts fit in exactly with the 

 common knowledge that the twilight hour is the most 

 dangerous one in malarial regions. Moreover, the three 

 species in question, and especially the first, enter houses 

 much more readily than others. 



Another important fact is that the mosquitoes of malarial 

 districts, especially the guilty ones, rarely ascend to a 

 great altitude. Therefore, in houses, the rooms of the 

 second and third flats are not visited much by these pests, 

 and this fact agrees well with the well-known comparative 

 salubrity of these higher rooms. 



It must always be borne in mind that in order to produce 

 fever in a healthy person by its bite the mosquito must 

 itself have previon sly bitten someone already stricken with 

 illness, and therefore of necessity only a small proportion 

 of the insects can be dangerous, even in a badly-infested 

 locality. The greater number of them bite domestic 

 animals, such as oxen, horses, pigs, dogs, pigeons, fowls, 

 etc., as well as man. One might, therefore, be bitten 

 thousands of times without being inoculated with the 

 baciUus, while, on the other hand, a single bite might be 

 suflicient. These possibilities must be taken into con- 

 sideration when we read of the failure of the early 

 experiments to demonstrate the actual transference of the 

 bacillus from the blood of the patient to the body of the 

 insect. In a joint note published by the three investigators, 

 Bastianelli, Bignami, and Grassi, they announce that they 

 have been able to follow with certainty certain phases in 

 the development of a bacillus in a portion of the alimentary 

 tract of AnojJu'les claviger. The specimen examined had been 

 made to suck the blood of patients suffering from malarial 

 fever, and the different phases observed seem to correspond 

 to some described by Ross in the case of a bacterial parasite 

 in birds. In a room where four malarial patients lived, 

 these authorities collected half a dozen Cule.v pipiem, four 

 AnophAes clarii/er, and one of another species. The 

 examination of all these insects proved without result, 

 except in the case of two of the AnopJu-hs, which yielded 

 bacilli in the stages of development just alluded to. In 

 an appendix to this communication, the same authors 

 state that they have succeeded in producing one of the 

 varieties of malarial fever in a patient solely through the 

 effect of bites made by this same species. The man was 

 certainly not previously suffering from malaria, and lived 

 in a place certainly free from the disease. They have also 

 obtained, within the alimentary tract of the insect, later 

 stages in the development of the bacillus than those men- 

 tioned in the account of their previous experiments. 



Grassi records it as his conviction that not only do 

 mosquitoes convey the infection of malaria, but they are 

 probably the onhj means by which the disease is spread. 

 This is a bold statement, and the author of it answers one 

 or two objections that might be raised against it. One is 

 that cases of malaria sometimes develop in great numbers 

 after a heavy shower of rain. Grassi points out that these 

 may be merely relapses of the fever, and that also before 

 these showers mosquitoes are particularly troublesome. 

 Many cases of malaria were reported to the Professor on 

 very high medical authority as having been developed in 

 places free from the presence of mosquitoes. In all the 

 cases he was able to investigate, however, there was 

 unmistakable evidence that the attacks of such insects 

 had intervened. 



I might go on multiplying these remarkable relationships 

 to some length further, but must now draw my abstract 



to a conclusion. In so doing I can only say with the 

 Professor, who has furnished the facts and conclusions 

 upon which these remarks have been based, that the 

 Investigation of malaria is entering upon a new phase, 

 and we can now indulge a little more than formerly the 

 hope of being able soon to battle successfully with malaria 

 in all its forms. It would not be difficult to make any 

 particular species of mosquito rare in a malarial district 

 by a wholesale destruction of the grubs. 



TWO MONTHS ON THE GUADALQUIVER. 



By Habrt F. Witherby, f.z.s., m.b.o.u. 

 n.— THE MARISMAS. 



THE small creek in which we were anchored proved 

 a pleasant spot, at all events from our point of 

 view. Birds were plentiful all around us, not 

 only during the hot and glaring day, but also at 

 night, when their notes — some well-known to us, 

 some unknown, wUd and weird — formed pleasing variations 

 to the metallic buzz of the persistent mosquito. 



This part of the marismas consists of dry caked mud, 

 covered with short grass and dwarf bog plants. At in- 

 tervals, even this scanty vegetation ceases altogether and 

 mud and water reign supreme. These patches of water, 

 some of which are very large, are called lufias. They are 

 quite shallow, being seldom more than two feet in depth, 

 and they are encircled by a belt of dry mud, the surface of 

 which is pitted with hoof marks, and cracked in every con- 

 ceivable direction. Being a luxurious feeding place for 

 ducks, geese, and all wading birds, a lucia forms a perfect 

 Eden for that eccentric being, the ornithologist. 



To deal first with the dry land. Within a few yards of 

 our camp were the nests of two different species of larks 

 very common in this district. One, the calandra lark, - is 

 a veritable giant amongst larks, being almost the size of a 

 song thrush. We nearly walked upon this bird before she 

 rose from her nest, and flew up with a tremendous flutter, 

 tumbling in her flight, and running along the ground in 

 front of us with trailing wings. The calandra has a bold, 

 bright song, uttered when the bird is on the wing, and, 

 like our skylark, it is given to imitating the notes of other 

 birds. A few steps away from the calandra's nest we 

 flushed a very small lark, which, unlike the calandra, rose 

 quietly from her nest and disappeared. This was the 

 Andalusian short-toed lark,f discovered by Lord Lilford 

 in 1872, and first described by Mr. H. E. Dresser in his 

 " Birds of Europe." These little larks, which are very 

 numerous in the m<irism(is, seem to be peculiar to this part 

 of the world. They do not soar like the calandra and the 

 skylark, but take short, upward flights, singing as they 

 go, and, returning to the ground or a low bush, finish 

 twittering there. We heard them imitate the notes of 

 many birds — such as stilts and redshanks. By the 8th 

 of April their nests were numerous. Those we found were 

 invariably built of dry grass and fine roots, lined with a 

 few feathers, and placed in a slight hollow in the ground, 

 often hidden by a tuft of grass or a small bush. The 

 only other diminutive bird that was at all common in this 

 Bcorched-up wilderness was a beautiful blue and yellow 

 wagtail — the blue headed wagtail. [ 



Many peewits ; had their eggs or young amongst the grass, 

 and the eft'orts of the parents to drive off' the birds of prey 

 afforded us constant amusement. They devoted their 



• Melanocorypha calandra. 

 X Motacilla flava. 



+ Calandrella bcetica. 

 § Vanellus vulgaris. 



