i6o 



NATURE 



[Dec, 27, 1877 



There are two important questions to be answered. 

 I. Are the pollen-sacs mere enlargements of the leaf- 

 substance of the staminal leaf, or are they special deve- 

 lopments somewhat like "emergence's"? 2. Do these 

 sacs belong to the under side, upper side, or both sides 

 of the leaf ; or are there differences of position in different 

 plants ? 



Cassini and Roeper held that the pollen-sacs were 

 cavities in the leaf-parenchyma, two forming on each side 

 of the leaf, so that the margin of the leaf corresponded to 

 the suture between the sacs. Mohl considered this view 

 only to hold for certain cases, as the Euphorbiacese, and 

 found, what Bischoff had already pointed out, that in all 

 examples examined, as in poppy, rose, and nigella, the 

 four pollen sacs were placed on the ttpper side of the leaf, 

 and that the margin of the leaf ran along the two posterior 

 or lower loculaments. Mohl did not consider the sacs as 

 "emergences," and differing morphologically from the 

 true leaf, as he says that the connective represents the 

 central portion of the modified leaf, while the loculaments 

 are the thick swollen lateral halves, which become con- 

 tracted in length and breadth. Mohl considered that in 

 the plants with extrorse anthers both the loculaments of 

 each anther lobe were developed on the under side of the 

 leaf. Alexander Braun pointed out in 1851 that the 

 anthers were produced by doubling of the lamina (Ueber- 

 spreitung). This view was confirmed by Wydler in 1852, 

 who compared the anther to the abnormal double lamina 

 in the leaf of Bignonia. 



Sachs considers the anthers to be appendages of the 

 leaf. He compares each loculament in the anther of 

 Cycads and Cupressineas to Sporangia ; the four pollen- 

 sacs in the Metasperms being " emergences " from the 

 upper side of the leaf, those of the Archisperms from the 

 lower side. Braun still further examined the subject and 

 confirmed his original views, namely, that the pollen-sacs 

 do not belong to a simple leaf, but to one with a double 

 lamina, the doubling due to the formation of an *' emer- 

 gence " (in Karl Schimper's, not in Warming and Sachs' 

 sense). The two upper anther sacs belong to the 

 " emergence," the two posterior to the original lamina of 

 the leaf. Celakovsky in the paper now before us departs 

 from the views published by him in Flora for 1874, 

 and fully confirms the views of Braun and Wydler. 



The second part of vol. xi. contains five papers by 

 Pfitzer, Koch, Reinke, and Reinsch. Dr. Pfitzer's paper 

 is on the rapidity of the current of water in the plants. 

 It contains an elaborate series of researches, the first on 

 the movement of leaves due to the absorption of water by 

 the stem and root ; the second by means of solution of 

 lithium. Dr. McNab's experiments are extended and 

 confirmed, but the astonishing rapidity of 22 metres per 

 hour was observed in Helianthus annus, the greatest 

 rapidity observed by Dr. McNab being 40 inches per 

 hour in Primus Lauro-cerasus. Pfitzer also uses a solu- 

 tion of soluble indigo carmine 4 parts to 1,000, and finds 

 that it is superior to solution of lithium, as it can be 

 detected at once instead of using the spectroscope. 



The second paper is by Dr. Ludwig Koch, on the 

 development of the seeds of Orobanchaceas. The deve- 

 lopment of the anatropal ovule, with one integument is 

 described, and the development of the embryo. This 

 agrees with the description given by Hanstein, of the 



embryo of Capsella. The endosperm is formed of divi- 

 sions of embryo-sac, which contains antipodal vesicles 

 before fertilisation. The third and fourth papers are by 

 Prof. Reinke, both on the development and reproduction 

 ofalgae, of the genera Phyllitis,Scytosiphon,Asperococcus, 

 and Bangia, the observations having been made at the 

 Zoological Station at Naples, during the winters of 1875 

 and 1876. 



The last paper is by Reinsch : " Observations on new 

 Saprolegnies, on parasites in cells of Desmedics, and 

 on the * Spinous Spheres ' in Achyla." A number of new 

 species and genera are described and fully illustrated. 



W. R. M'Nab 



MOVING DIAGRAMS OF MACHINERY 

 Patent Working Drawings. By H. and T. C. Batchelor 

 (London : Macmillan and Co.) 

 A LL who are engaged in the teaching of kinematics 

 -^^ and of applied mechanics must ofcen have ic brought 

 forcibly before them the difficulty that exists in making 

 even comparatively simple mechanical motions intelli- 

 gible to students by means of ordinary drawings and 

 diagrams, while the more complex motions and com- 

 binations can hardly be treated of at all profitably with- 

 out the aid of working models, which are very expensive, 

 and take up a great deal of space. Again, inventors and the 

 proprietors of patented mechanical inventions, are often at 

 a loss to explain to unscientific or uninitiated persons the 

 advantages of their systems, and costly working models 

 have to be resorted to in order to avoid the mystification 

 which ordinary mechanical drawings often produce in the 

 minds of those not accustomed to them, or who are not 

 versed in the principles of mechanics. 



To supply this recognised need of teachers and others, 

 Messrs. H. and T. C, Batchelor have designed and worked 

 out a most ingenious system which combines the mechanical 

 movements of a model with the flatness and clearness of a 

 diagram. The name "Working Drawings" applied to these 

 diagrams is somewhat misleading, especially to engineers 

 and others accustomed to this term as having a distinct and 

 special meaning, namely, drawings made for and used by 

 the workmen employed upon the construction of machinery 

 to worK from. Working drawings are essentially drawings 

 for the workshop, and that is the universal acceptation 

 of the word. The meaning attached to it by Messrs. 

 Batchelor is, however, very different; it is drawings 

 which will work moving diagrams. This sense is, 

 perhaps, more critically correct, but as another meaning 

 is the generally accepted one, we cannot but think that it 

 would have been wise if a name had been given to these 

 diagrams more descriptive of what they are. Tney are, 

 in fact, moving diagrams or sectional working models of 

 machines, the fixed parts being lithographed as a back- 

 ground upon a firm cardboard mount, and the movino^ 

 parts being also lithographed on card, but cut out and 

 jointed together by most ingenious mechanical contri- 

 vances ; the whole being no thicker than a sheet of stout 

 cardboard. 



The perfection of the centres upon which the various 

 parts revolve or are pivoted together must be seen to be 

 adequately appreciated, for while these centres allow 

 perfect ease of motion to all the parts, they are absolutely 



