LARKSPUR POISONING OP LIVE SHOCK. 19 



cross sections of the main stem of the plant were made without refer- 

 ence to any particular point in the stem. In the case of Delphinium 

 harheyi and Z>. menziesii and Aconitum hakeri^ sections were made 

 from the subterranean portion of the stem, the petiole, and the 

 peduncle. A photomicrograph was made of a portion of a section of 

 a stem of each species, all the photographs being magnified 65 

 diameters. 



The sections of course showed certain characteristics typical of the 

 Ranunculacese, the most noticeable being the form and disposition of 

 the fibrovascular bundles. The bundles are of the closed collateral 

 type and are isolated, being separated by wide medullary rays. The 

 xylem mass has in cross section a somewhat V-shaped appearance, the 

 arms of the V partially inclosing the cambium and phloem. There 

 is no interfascicular cambium. This type of bundle is common to 

 the Ranunculacese, but is found almost nowhere else among the dicot- 

 yledons (Solereder, 1908, p. 18, and Jeliffe, 1899, p. 339). Another 

 feature of the bundle peculiar to the Ranunculacese among dicotyle- 

 dons is that the phloem consists only of sieve tubes and companion 

 cells, with no phloem parenchyma (Strasburger, 1908, p. 113). 

 These facts in regard to the fibrovascular bundles serve to differen- 

 tiate the Ranunculaceaj from other dicotyledons, but are also points 

 of resemblance to some of the monocotyledons. Therefore in identi- 

 fying larkspurs in the stomach contents of poisoned cattle it was 

 necessary to differentiate carefully from some of the grasses when 

 only fragments of the stem could be obtained. 



The genus Delphinium has a characteristic stem structure, as shown 

 by cross sections. Vesque, 1881, page 28, says that it is impossible to 

 distinguish anatomically the genera of the Eanunculacese, but that 

 certain groups of genera can be recognized, and he places Aconitum 

 and Delphinium in one group. Myer, 1885, page 46, in his key, gives 

 means of distinguishing both Delphinium and Aconitum, the latter 

 being differentiated from Delphinium by the presence of a complete 

 ring of sclerenchyma outside the fibrovascular bundles. 



In cross section the external circumference of a Delphinium stem 

 is either approximately circular or approaching an octagonal shape, 

 and the stem is hollow. It is covered externally by a layer of epi- 

 dermal cells whose outside walls form a thickened cuticle. The epi- 

 dermis usually bears unicellular hairs of varying shape, size, and 

 number, and is pierced by simple stomata. Beneath the epidermis 

 there is a layer of hypodermal cells similar to those of the epidermis 

 but without thickened walls. Inside the hypodermis there are two 

 to five rows of cortical parenchyma cells, bearing chlorophyll, and 

 arranged loosely with intercellular spaces. In one species it was 

 possible to distinguish an endodermis, but as a rule the endodermis 

 can not be distinguished from the other cells of the pericycle. The 



