236 



THE AMERICAN MONTHLY 



[December, 



Death of Robert B. Tolles. — 

 Mr. R. B. Tolles, one of the best 

 known makers of microscopes and 

 objectives the world has ever known, 

 died on Saturday, the 17th of Novem- 

 ber. We defer an extended notice of 

 his life and accomplishments for a 

 future article, the time for its prepa- 

 ration being too short for this month's 

 Journal. Mr. Tolles leaves a wide 

 circle of friends, for he stood very- 

 high in the opinions of all who knew 

 him. 



Unity of Plant-structure, — 

 The simplest microscopic plants per- 

 form all the functions of plant-life as 

 perfectly as . do the more complex 

 members of the vegetable kingdom. 

 Through all the differentiations of tis- 

 sues which have taken place in the 

 development of the higher plants 

 from the simple cells — changes which 

 have resulted, for example, in the adap- 

 tation of special cells to certain func- 

 tions, such as assimilation and diges- 

 tion of food, respiration, circulation, 

 etc., — there has been maintained a 

 perfect interdependence and unity of 

 action, which has been especially re- 

 cognized by Strasburger, who has treat- 

 ed the subject in an able manner. 

 Perhaps the most striking of all mani- 

 festations of the intimate relations be- 

 tween the different parts of a plant, are 

 seen in the movements of the so-called 

 sensitive plants, in which an irritation 

 of any part is transferred, in some 

 unknown manner, along the stems and 

 branches to other parts. 



Recent researches with the micro- 

 scope have indicated that the impulses 

 are conveyed through the protoplasm 

 of the cells, which, in some cases at 

 least, is continuous from cell to cell. 

 The fact that in the sensitive plant the 

 protoplasm of the cells is affected by 

 irritation has long been known; but 

 how the irritation, or the protoplasmic 

 change produced by it, is conveyed 

 from cell to cell has not been under- 

 stood. One method of investigation 

 which has led to the discovery above 

 mentioned is, in brief, as follows : 



Very thin radial and tangential sec- 

 tions of the cortical tissue of the young 

 stems of laburnum, the buds of the 

 sycamore, and of the stems and base 

 of the leaves of other plants were pre- 

 pared, the best results being from 

 specimens obtained in January. The 

 sections were then treated with di- 

 lute, and then from 20 to 48 hours 

 with concentrated sulphuric acid. 

 After careful washing with water, the 

 sections were prepared for examina- 

 tion with glycerin. All these opera- 

 tions were performed with the speci-' 

 men on the slide. The whole of the 

 cell-wall is thus removed and often the 

 intercellular substance also. In this 

 way it was found, by Mr. Hill house, 

 that the so-called pitted cells commu- 

 nicate with each other by openings 

 through which protoplasmic threads 

 extend; but these threads can only 

 be detected after removal of the cell- 

 walls, as in the manner above de- 

 scribed, being too delicate to be ob- 

 served in situ. After the cell-walls are 

 destroyed the connecting filaments 

 may be seen. These researches, 

 which are confirmatory of those of 

 other observers, indicate how the im- 

 pulses which cause the movements of 

 Mimosa, for example, are conveyed 

 along the cells, and it would be well 

 worth the labor of micros :opists du- 

 ring the winter months, — even for 

 amateurs who are too often loth to 

 undertake observations of a delicate 

 nature — to prepare specimens illus- 

 trative of the interesting facts thus 

 discovered. Such preparations would 

 have more than a special interest to 

 the microscopist, for no botanist or 

 physiologist would pass them by with- 

 out a careful examination. 



The Army Medical Museum. — 

 Probably the most complete and well- 

 chosen collection of apparatus for 

 microscopic work in the country is at 

 the Army Medical Museum at Wash- 

 ington, brought together by Dr. J. J. 

 Woodward, and used by him in his 

 investigations. That apparatus has 

 been lying idle for a long time, owing 



