NATURAL SCIENCE NEWS. 



75 



Imbeciles Among Plants and 

 Animals. 



Every one understands what is 

 meant by the imbecile, when speak- 

 ing of human beings. The mental 

 development of the child is check- 

 ed, and even when such a child 

 reaches the age of manhood, it is 

 still but a child in its feelings and 

 wants; but it is not alone among 

 human beings that the character- 

 istics of imbecility are found. In 

 almost all trees, the characteris- 

 tics of the foliage or the habit are 

 very different during the first few 

 months of existence than they are 

 in after life. There is a matured 

 characteristic as well as an infan- 

 tile one. The Tulip Tree for in- 

 stance has its first set of leaves en- 

 tire, without any appearance of 

 the lobe or the truncate termina- 

 tion which it assumes in old age; 

 but sometimes these juvenile char- 

 acteristics will be maintained 

 through life, — and then we have 

 what is known as the Liriodendron 

 intcgrifolia, — that is to say the En- 

 tire-leaved Tulip Tree. This is 

 more particularly marked among 

 evergreens. During the first year 

 of the arbor-vitas, pinus, cupressus, 

 retinospora and similar plants, the 

 leaves are heath-like, that is ex- 

 tending from the stem quite separ- 

 ate and distinct; but occasionally 

 there are individuals carrying these 

 characteristics through life; and 

 many of the •so-called Japanese 

 species are merely vegetable imbe- 

 ciles. 



It is not uncommon for acute ob- 

 servers to find branches assume 

 their adult form in many individ- 

 uals in this imbecile class. Just 

 as in the case of human beings 

 there are occasionally instances 

 where imbeciles assume matured 

 characteristics. This is also true 

 of the animal world. A friend of 

 the writer has an aquarium in which 

 tad-poles as well as other aquatic 

 creatures are raised. As every one 

 who is acquainted with the com- 

 monest events in natural history 

 is aware, the tad-pole during its 

 first season throws off its tail, 

 pushes its legs and becomes a frog. 

 In the case of the friend referred 

 to, he has a tad-pole which thrust 

 out its legs and then ceased to de- 

 velop further. After three years 

 it is still a tad-pole with its two 

 frog legs, retaining its tail and in 

 all other respects it is a tad-pole 

 with the tad-pole characteristic in- 

 tact. It may be termed a froggy 

 imbecile. — Medians'' Monthly for 

 June. 



Exfoliation of the Tortoise. 



I read an article in the Natural 

 Science News, some time past on 

 the exfoliation of the tortoise, and 

 imagine my surprise on finding 

 one while riding through the woods 

 on May 2d. All the leaves were 

 off the back and down one side 

 leaving the outer row intact, ex- 

 cepting one plate was gone, just 

 above the right hind leg. At first 

 it looks like bone or dead shell, but 

 in the course of a few days it be- 

 gins to look sleek, and a dark spot 

 appears and spreads until now the 

 dorsal piates are almost black. I 

 removed one fragment which was 

 loose and enclose it. The bone has 

 not begun to change yet, but one 

 removed ten days has become 

 sleek. All the remaining scales 

 are loose, and the process of des- 

 quamation is in full force. I write 

 to say that if any one you know 

 wishes to have it and watch the 

 process, or take notes and data, I 

 will box and ship provided they 

 pay expressage. I am aivay from 

 home most of my time and cannot 

 do it. 



I. P. Canfield, D. D. S., 



Paw Paw, W. Ya. 



Keokuk Geology. 



Keokuk, Iowa has a geological 

 record that in some respects is 

 quite unique. , 12 miles north of 

 the city, the great Father of 

 Waters begins a headlong descent 

 of feet in that distance, known 



as the Des Moines Rapids, which 

 caused such serious interruption 

 to navigation, that the govern- 

 ment thought it advisable to con- 

 struct a canal to obviate the diffi- 

 culty. The rock is limestone, of 

 a very hard and durable nature. 

 Some of it actually passing the 

 border line into marble. 



Like other Palaeozoic rocks, 

 these strata had their birth in an 

 open sea. And they are mainly 

 formed of the remains of animal 

 life, every one of the five sub -king- 

 doms of which, is represented in 

 these rock strata that underlie the 

 citv. Protozoa are not largely re- 

 presented by fossil remains. Two 

 species of sponge are known. But 

 of Radiates there is a better show- 

 ing; for Zaplircntcs is a rather com- 

 mon coral, and Crinoid remains 

 in the way of detached broken 

 arms and stems are plenty. The 

 perfect fossil is not easily obtained, 

 but sometimes many species are 

 found crowded together in a small 



space, so that from an area of ten 

 feet square, 200 have been procur- 

 ed, seeming to show either a gre- 

 garious habit in the animal, or a 

 retreat into protected places for 

 safety, or a more congenial place 

 of growth because of currents then 

 existing, or in the amount of food 

 wafted to these favored localities. 



The following genera are most 

 largely represented viz: Actinocri- 

 m/s, Forbesiocrinus, Cyathocrinus, 

 Platycrinus and Agariocrinits. 



The Molluscan remains are well 

 represented by Brachiopods, of 

 which the genus Spirifer is, per- 

 haps most abundant, yielding 

 seven or eight species. Also Or- 

 this is quite abundant. The Gas- 

 terpods make a poor showing. 



Of Vertebrates there are the re- 

 mains of many Selacian, or Cartil- 

 age fish, in the way of teeth and 

 fin spines. So that taking the 

 number of these found in this lo- 

 cality, seems rather to add another 

 doubt whether the Sub-Carboni- 

 ferous is not really better entitled 

 to be called the '-'Age of Fish" 

 than the Devonian, as that has 

 usually been styled. 



The upper beds of ihe Keokuk 

 formation properly are famed for 

 their Geodes. I think a true ex- 

 planation of how these have been 

 formed is yet wanting. It is easy 

 enough to call them '•'Genus Bi- 

 opella" but how formed this inte- 

 rior lining of crystals of quartz or 

 calciteor both, as the case may be, 

 sometimes almost to the oblitera- 

 tion of the internal space. The 

 Geode sometimes contains liquid, 

 but if all had originally been filled 

 with the most concentrated solu- 

 tion of silica or lime carbonate, it 

 would, by evaporation, be entirely 

 insufficient in quantity, to yield the 

 interior lining of crystals. After 

 the crust of the geode was formed, 

 being very generally impervious 

 to water, no solution holding ma- 

 terial could find its way inside. 

 Besides, when at home in their 

 native bed, the matrix rock is a 

 rather soft magnesia limestone, 

 from which the desired material 

 for the included crystals, we 

 would rather suspect to be Dolo- 

 mite or Calcite and not Quartz, 

 which is most common. When 

 the matrix rock in this vicinity ap- 

 proaches to a purer limestone in 

 constitution, the geode seems to 

 vanish — cavities in the rocks, often 

 beautifully lined with crystals, tak- 

 ing its place, but the exterior shell 

 is obliterated. It has adhered to, 

 and become a part of the surround- 

 ing rock, and is not separable from 

 it and the cavity very often is not 



