HARDWICKE'S SCIENCE-GOSSIP. 



205 



seeds have been fertilized throughout, we can observe 

 the stages indicated, from the centre to the outside 

 (that is, from figs. 135 to 143), with never-failing regu- 

 larity. One more sketch, fig. 144, much enlarged, 

 represents the stamens and anthers, as joined, laid 

 open. Soon after the blossom opens, the stamens, 

 with pistil enclosed, appear above the top. I 

 observed bees frequently visit the flowers and thrust 

 their proboscides down the corolla so as to reach the 

 nectar cups, at the same time rubbing their heads on 

 the anthers and taking off pollen. I also observed 

 that, as soon as the pistil appeared, the stamens 

 began to lower themselves, and I believe this was 

 due partly to shrinkage and partly to the bees 

 continually pressing with their heads in order that 

 they might the better reach the nectar ; but I should 

 say that as soon as the pistil has opened as much as 

 to form an angle of 45 , it also would exert its 

 influence and continue to do so until the anthers were 

 brought to the level of the top of the corolla. The 

 pistils are only capable of receiving pollen for fertil- 

 izing purposes when open ; so that a bee, rubbing its 

 head against anthers where the pistil has neither 

 appeared nor opened, would collect pollen, which it 

 would deposit on the open pistil of another blossom, 

 perhaps on another plant, thus securing cross- 

 fertilization. 



There is yet another matter to discuss which is of 

 no little importance. Whence come the stamens and 

 pistil The corolla from a ray floret, the ray floret 

 from a bract, the bract from a leaf, is clear enough. 

 I am inclined to think, though I have not conclusive 

 evidence, that stamens and pistil are developed spines. 

 There are spines on the outside of the corolla, but 

 none on the inside. There are no spines at all on 

 the stamens ; there are none on the lower part of the 

 pistil, and the fact of there being spines on the upper 

 part will not much affect the argument If we look 

 at a ray floret under the microscope, we can clearly 

 see delicate spines on the under-side, spines on the 

 rudimentary achene and the wings, and a few spines 

 on the uppermost side, just above the neck. It is not 

 unusual when one organ or part of a plant is reduced 

 in size for another to be increased. In order to 

 evolve a blossom from a ray floret, the latter must 

 dwindle, besides closing in, and it is not unlikely that 

 the extra nourishment, thus set free, may go towards 

 increasing the internal spines, or some of them, until 

 they develop into stamens and pistil. 



The first number of the "Bulletin of the Des 

 Moines Academy of Science" has been published. 

 The object of the Academy is to issue a series of 

 publications to cover more or less completely the 

 natural history of the State of Iowa, and this first 

 number contains a geographic catalogue of the 

 Unionidce of the Mississippi Valley, by R. Ellsworth 

 Call. 



TEETH OF FLIES. 

 By W. H. Harris. 

 No. VII. 

 CARICEA TIGRINA, Fab. 



CARICEA TIGRINA, from which the present 

 illustration is taken, is a rather small but 

 prettily formed fly, and may be taken rather plenti- 

 fully by sweeping among grass during the whole of 

 the summer months. When once its acquaintance 

 is made no difficulty will be experienced in identi- 

 fying it on subsequent occasions. 



It is about the size of Musca domestica minor, ashy 

 grey in colour, with two distinct darkish lines on the 

 thorax. An examination with a lens shows this is- 

 caused partly by its being clad with rather strong 

 hairs on these parts and partly by a deposit of pig- 

 ment in the integument around the basis of the 

 larger hairs. 



There are eleven distinct spots of this character on 

 the dorsal and lateral parts of the abdomen, arranged 

 in the following manner. The segment immediately- 

 succeeding the thorax bears one spot centrally situated. 

 The next segment has two such spots separated 

 by about the thirty-second part of an inch, the two- 

 succeeding segments have each four such marks, thus- 

 giving this part of the insect a very pretty appearance. 

 The eyes are very dark, surrounded with a ring of 

 the body colour, the thigh is of the same shade, the 

 tibia rusty brown, while the tarsus is very dark ; the 

 proboscis for a considerable portion of its length is 

 hard, dark, and highly polished, incapable of being 

 wholly withdrawn as in many species of the 

 Anthomyiidse. 



The general character of the Caricea, as given by- 

 Mr. R. H. Meade in an annotated list of the British 

 Anthomyiidse, will be found in " The Entomologists' 

 Monthly Magazine," vol. 20, p. 60. For the benefit 

 of those readers who do not possess the work, I 

 append the description thus given : acknowledging 

 my indebtedness to that gentleman for the identifica- 

 tion of this creature. 



" Eyes bare, widely separated by a space of nearly 

 equal width in both sexes ; arista with long hairs ; 

 alulets well developed ; tibiae all armed at their 

 apices with four or five spines ; anal vein rather short, 

 only reaching about half-way from the base to the 

 margin of the wing." 



The lobes terminating the proboscis are small 

 and not readily expanded. To display this portion 

 of the mouth, a method similar to that adopted in 

 the case of Stomoxys calcitrans must be employed - y 

 and if the incision is made at the right spot an ex- 

 ceedingly symmetrical set of organs will be revealed. 



In this case a departure has been made from the 

 course hitherto followed in these notes, the whole set 

 of teeth being given. 



The dentition of this creature consists of two 

 distinct types, which are comparable only with organs 



