October 1, 1892.] 



KNOWLEDGE 



183 



its next move must be to enter the body of a bee larva, 

 wbioh will tlms be selected as its lifelong host. Now here 

 arises a very nice question ; in order to take this step in 

 its advancement, will it avad the Sti/lojis larva to remain 

 on the body of the bee that produced it, or is it necessary 

 that it should leave its foster parent and seek out an 

 unstylopized specimen ? This evidently turns again on 

 the question whether the stylopized bee is capable of re- 

 producing its kind, a question somewhat more complex 

 than miijht at first be imagined, and in our endeavours to 

 answer it we must consider for a while what effects the 

 parasitism of the Sti/lnji.-: produces on the bee. These are 

 very considerable, and may be classified into two groups, 

 internal and external effects. The internal effects run 

 chiefly in the direction of the reduction in size of the 

 various organs of the bee's abdomen. It is obvious that 

 the presence of so large a foreign body amongst the bee's 

 vitals must produce pressure upon surrounding parts and 

 interfere with their proper growth and development. 

 Thus the digestive tract of the bee is lessened in size 

 and its walls become thinner, whereby the fluids it 

 contains more easily pass through into the bcdy of the 

 parasite. But the eii'ect is most marked in the case of 

 the reproductive organs, which are much reduced in 

 size and retarded in development. Both sexes of the bees 

 are liable to the attack of the parasite, though the females, 

 as a rule, seem to be the more frequently selected. The 

 exact amount of interference with the bee's well-being 

 which the parasite produces varies a good deal, according 

 to the species of bee, the sex of both parasite and host, and 

 the number of parasites present, which may be as much as 

 four or five in one specimen, though most frecjuently they 

 are solitary. Dissection of the bee's body has, therefore, 

 led to somewhat conflicting results, some observers 

 chronicling the almost entire abortion of the reproductive 

 organs and the entire absence of their characteristic 

 products, and others noting only their reduction in size 

 and retardation in development. 



But even supposing the female stylopized bee to be able 

 to produce fertile eggs, this is by no means all that is 

 necessary to ensure the production of a brood. The young 

 bee grub must be provided with food, and to this end poUen 

 must be collected, and this cannot be done in the absence 

 of the pollen-collecting organs. This leads us to consider 

 the external changes produced by stylopizatiou. The exact 

 details here again will differ in difl'erent cases. Our present 

 business is with the female bee, and we will therefore 

 consider only the changes produced in the external appear- 

 ance of a female bee of the genus Andremi. These have 

 been very clearly pointed out by Prof. Perez in a commu- 

 nication made to the Linnsuan Society of Bordeaux, and his 

 observations have been confirmed by other observers. The 

 head of the bee becomes smaller and the abdomen more 

 globose, while the hairs tend to become less densely 

 distributed and paler in tint, and to form bands at the 

 edges of the segments. The two chief parts of the pollen- 

 collecting apparatus in an Andrcmi consist of a brush of 

 hairs on the outside of the posterior tibije, and a little curl 

 or lock of rather long hairs on the posterior trochanters, 

 the minute joint which is situated between the basal joint 

 which attaches the leg to the body and the thigh. Now in 

 the stylopized bee these masses of hair l)ecome shorter, 

 and therefore less fitted for the collection of pollen. In fact, 

 ill most respects the female bee approaches the condition 

 of the male, while the stylopized male, on the other hand, 

 tends to assume the characters of the female. M. Perez, 

 who has examined great numbers of these bees, says that he 

 has only met with one single specimen of a female stylopized 

 Andivna which was carrying poUen on its collecting brushes. 



Now if it be the case, as is generally believed, that a bee 

 does not collect pollen till it is fertilized, this would seem 

 to indicate that stylopized bees do not become fertilized. 

 If this be so, then, evidently, the only chance that the 

 newly-hatched larva;, which we left scrambling about 

 amongst the forest of hairs on the body of their foster 

 parent, have of further development is to dismount their 

 present steed and seek another which is not thus 

 handicapped ; and it is clear that such a step will, under 

 any circumstances, be absolutely necessary in the case of 

 those produced from lunlf bees. This is evidently, then, 

 a dangerous and critical period in the little creature's 

 career, and amid its many risks no doubt vast numbers 

 perish, just as do the Mi-hili larvffi. That such must be 

 the case is indeed evident from the contrast between the 

 multitudes of larvie produced and the comparative scarcity 

 of the perfect insect. 



Suppose, however, that a larva has successfully gained 

 the back of an unstylopized female bee, and is by her 

 conveyed to the cell she has made and provisioned for her 

 own larva. The Sti/hi/is larva now dismounts, and in some 

 way insinuates itself into the body of the bee grub, 

 subsequently casting its skin and losing its legs, becoming 

 itself maggot-like, anil thus adapted to the new phase of 

 life upon which it has entered. In this larva it remains, 

 growing with its growth, and passing through its own 

 metamorphoses as its host does, so that it becomes 

 matured at the same time that the bee puts on its final 

 form. During its preliminary stages it lies with its head 

 towards the head of the bee, tlie position in which it made 

 its entrance into the bee's body, but previously to maturing 

 it reverses its position, and thus is enabled, if a male, to 

 make its exit into the outside world head firic, just as 

 Kirby witnessed it, or if a female, is placed in a suitable 

 position for fulfilling the functions that yet remain for her 

 befoi'e she can give birth to her enormously multitudinous 

 family. Having thus followed the course of the development 

 of the Sti/hiji.s throughout its life-history, we see that it does 

 not, as so many internal parasites do, cause the death of the 

 individual host, though, if the bees are really rendered abor- 

 tive by its presence, it tends to the extinction of the .^im-ics. 



Stylopization, in some cases, so greatly alters the bee's 

 appearance as to have led to the erroneous creation of 

 pairs of species, the stylopized form having been described 

 and named as a distinct species from the bee in its natural 

 condition. Besides the sexual reversals already enumerated, 

 there is one very curious result of stylopization for which 

 it is difficult to find a physiological explanation ; this is the 

 alteration that takes place in the colour of the face in some 

 bees. There are certain bees of the genus Andrena, notably 

 A. Iiibiiilis, in which the face of the male is yellowish white, 

 while that of the female is blackish. Stylopized specimens 

 of such species, if they are males, tend to have the pale 

 parts reduced in size and altered in shape, while the 

 females show a tendency to appear with spots of yellow on 

 the usually dark face. 



Erratu.m. — In Mr. E. A. Butler's article, " Bee 

 Parasites," on page 164 of our last number, the inscription 

 under Fig. 8 should read, " Stages of larva of SiUiris 

 iinirii'is. (After Fabre)." 



I 



THE FUEL OF THE BLAST FURNACE. 



By Vauoii.vn Counish, M.Sc, F.C.S. 



N a former article (Knowledge, February, 1892) we 

 traced the progress of our knowledge of the element 

 carbon, from the time when it was recognized a.s a 

 reducing principle by means of which ores could be 

 made to yield the metah, to the time when Lavoisier 



